[3][4] His mother died in a car crash when Clarke was aged two and he and his brother, Wayne, were raised by his grandparents as his father was an alcoholic.

[6] His eldest daughter, Ellie, died on Valentine's Day 2022 in what was ruled as a suicide by an inquest, though Clarke maintains was "a cry for help that went drastically wrong".

Clarke made his first-team debut on 21 December 1996, coming on as a half-time substitute for Ben Sedgemore in a 2–1 defeat at Cardiff City.

While at Mansfield, he became a fan favourite due partly to his high work rate; he made 173 league and cup appearances for the club, scoring 27 goals.

The arrival of manager Neale Cooper saw Clarke's opportunities in the first-team in 2003–04 limited, as Eifion Williams was preferred on the right wing.

He was loaned out to Stockport County — managed by former Hartlepool boss Chris Turner —[16][12] to gain fitness in January, but this was cut short as Clarke picked up another knee problem after just one game.

[18] In September 2005 Clarke was loaned to Port Vale,[19][20] but played just two minutes after being utilised as a late substitute by manager Martin Foyle.

[33] After his first season, the "Whites" won promotion from the Southern League Premier Division via the play-offs, winning 3–2 on penalties after a 2–2 draw with Hednesford Town.

The team's success saw him strongly linked with the vacant management position at Hartlepool United in October 2012,[41] though he ultimately remained at Salisbury.

[42] In June 2013, Clarke was appointed as assistant manager of League Two club Bristol Rovers, supporting John Ward.

[43] Following another season of struggle at Rovers, Ward was moved to a role as Director of football and was replaced as manager by Clarke in March 2014.

[48] Clarke led Rovers to promotion with a 5–3 penalty shoot-out victory over Grimsby Town at Wembley Stadium in the 2015 Conference Premier play-off final on 17 May 2015, following a 1–1 draw after extra time.

[51] Clarke was named as Manager of the Month for March after winning six of seven games by "playing exciting and attacking football" according to head judge George Burley.

[53] Named as the Football League manager of the week, his citation stated that "Clarke has performed wonders as his men have stormed up the table".

[54] On 27 May 2016, Clarke turned down the opportunity to manage Championship club Leeds United and signed a new three-year contract with Bristol Rovers.

[58] During late March 2017, with his club sitting just outside the League One play off places, Norwich City were reported to be interested in Clarke following the sacking of previous manager Alex Neil.

[63] He was named as EFL manager of the week after overseeing a 6–0 win away at Northampton Town on 7 October despite missing his preferred centre-backs.

[69] He left his post on 13 December 2018 following a run of seven defeats in ten matches; at the time of his departure he was the fourth-longest serving manager in the EFL.

[71] He signed 16 players as 23 departed – including midfielder George Dobson, who was sold on to Sunderland – and got off to a poor start after Walsall picked up just one win the opening ten games of the 2019–20 campaign, with the team sound defensively but failing to create any chances in a 5–3–2 formation.

[74] Clarke went on to admit that the following campaign would likely see him focus more on youth as the club faced a challenging financial future due to the effects of the pandemic.

[80] He was nominated for the League Two Manager of the Month award after his team picked up 16 out of an available 18 points in April, conceding just a single goal in the process.

[83][84] Clarke and Flitcroft recruited 12 players for the start of the 2021–22 season, including Ben Garrity, Jamie Proctor and James Wilson.

[85] Clarke was named as September's Manager of the Month award after overseeing a run of three wins from four games which took his side into the automatic promotion places.

[88][89] Nine players left the club in the January transfer window, whilst eight signings were made, including Connor Hall and Chris Hussey.

[91][92] On 30 March, it was confirmed that Clarke would be returning to the club to support Crosby until the end of the season before taking charge again in the summer.

Clarke was sent off in extra-time of the second leg for an altercation with Swindon Town's Dion Conroy, and had to witness Vale's penalty shoot-out victory from the stands.

[98][99] Clarke was one of eleven managers who received special recognition at the 41st Football Writers Awards dinner for their work during the 2021–22 season.

[103] On 29 September 2023, Clarke signed a two-year deal to manage Cheltenham Town, who were bottom of League One without a victory or goal scored from their opening nine games of the 2023–24 season.

[113] Clarke is flexible with his formations and is open to different styles of playing rather than sticking to a rigid philosophy, believing that "adaptability is key".