Sinclair left Salisbury when the club were relegated two divisions after a breach of rules on unpaid debts, and he joined Stevenage of League Two on a free transfer in June 2010.

[5][6] Sinclair began his career as a trainee with Luton Town, and was a regular in the club's under-18 and reserve teams, where he played as a right winger.

[8] Sinclair did not breakthrough into the Luton first team during the 2007–08 season and was subsequently loaned out to Conference Premier club Salisbury City on 31 January 2008.

[13] Following his departure from Luton, Sinclair joined Salisbury City of the Conference Premier on a permanent basis, signing a two-year contract on 22 May 2008.

[13] Salisbury manager Nick Holmes stated that Sinclair impressed him during his loan spell and would play a major part in the club's upcoming season.

[14] The injury ultimately ruled him out of the first team for two months, and he returned to the starting eleven on 18 October 2008, playing 64 minutes in Salisbury's 2–0 defeat to Stevenage Borough.

[3] Sinclair made his Stevenage debut in the club's first ever Football League fixture, a 2–2 draw against Macclesfield Town on 7 August 2010, coming on as a substitute in the 71st-minute of the match.

[27] Having failed to make any first-team appearances for Stevenage that season as a result of the injury,[28] Sinclair joined League Two club Aldershot Town on a one-month loan agreement on 13 March 2012, in order to gain match fitness.

[34] Sinclair returned to Salisbury City, with the club competing in the Conference South, on 31 January 2013,[37] joining on a free transfer after leaving Stevenage by mutual consent.

[2] Ahead of the 2013–14 season, Sinclair signed a one-year contract extension to remain at Salisbury for their return to the Conference Premier.

[41] He started in the club's first game back in the first tier of non-League, a 1–0 defeat to Tamworth at the Raymond McEnhill Stadium on 10 August 2013.

[43] At the end of the season, in June 2014, Sinclair was one of three Salisbury players to join Conference Premier club Forest Green Rovers.

[44] Sinclair made his Forest Green debut on the opening day of the 2014–15 season on 9 August 2014, playing the whole match in a 1–0 away victory at Southport.

[47] He made 46 appearances and scored three times as Forest Green lost at the Conference Premier play-off semi-final stage to Bristol Rovers by a 3–0 aggregate scoreline.

[60] Sinclair scored three times in five matches during December,[2] and was subsequently named as the National League South Player of the Month.

[63] He scored four times in 12 games in the opening three months of the season,[2] including twice in a 5–0 FA Cup victory against Hemel Hempstead Town on 23 October 2018.

[65] Following his departure from Oxford City, Sinclair joined fellow National League South club Hemel Hempstead Town on 5 November 2018.

[66] Sinclair made his Hemel debut in the club's 2–1 home win against Gloucester City on 10 November 2018, scoring the first goal of the match.

[67] Sinclair scored four times in his first six games for Hemel, which included two second-half goals in a comeback victory at East Thurrock United on 17 November 2018.

[70] Sinclair joined Southern League Division One Central club Bedford Town on 16 July 2020,[71] signing a one-year contract.

[73] After spending time as a first-team coach at Dunstable Town, Sinclair was appointed as manager of Eynesbury Rovers in the United Counties League Premier Division South on 18 October 2021.

[75] Sinclair left Eynesbury in order to take on the role of first-team manager at Spartan South Midlands Football League Division One club Real Bedford on 10 May 2022.