Clare spent the majority of his career with the Castleford Tigers in the Super League across two spells, making over 100 appearances and scoring over 50 tries.

[10] On 8 September 2013, Clare scored 4 tries in Castleford's visit to local rivals Wakefield Trinity Wildcats on the final day of the season.

[12] He made 17 appearances and scored 11 tries for Castleford as the team finished 4th in Super League and reached the Challenge Cup final.

[13] He made 9 appearances and scored 4 tries for the Tigers, as well as playing for the York City Knights on dual registration, before his move to the Bradford Bulls was announced on 22 July.

He scored against Whitehaven (2 tries), the Swinton Lions (3 tries), the Leigh Centurions (3 tries), the London Broncos (1 try), Halifax (1 try), the Sheffield Eagles (1 try), the Dewsbury Rams (1 try), Workington Town (2 tries), Oldham (2 tries) and the Batley Bulldogs (2 tries).

[18] Clare later recalled that, after Bradford were placed in administration in November 2016, he "seriously considered quitting the game for good", saying, "The amount of emotional stress you go through takes its toll on you physically in the end.

[21] Leigh head coach Neil Jukes said: "James is someone we've admired and monitored for some while now, especially after his performance in our epic draw at Bradford last year.

Unfortunately, Clare suffered an anterior cruciate ligament injury in Leigh's pre-season win over the Dewsbury Rams on 29 January 2017.

[15] Leigh were defeated by the Catalans Dragons in the 2017 Million Pound Game, resulting in their relegation to the Championship and meaning all contracts became null and void, leaving other clubs free to approach Clare.

[27] After beginning the season at Halifax on dual registration, he played his first game since returning against the Salford Red Devils on 11 March, scoring a try.

[32] This included his second hat-trick for the Tigers on 12 July - this was his first Castleford treble since 2013 and it occurred, again, in a visit to local rivals Wakefield.

[36] In December 2020, it was announced that Clare had signed a two-year extension with Castleford,[37] with head coach Daryl Powell touting him as the team's "most improved player" and praising his hard work and commitment.

[36][38] Prior to the 2021 season, Clare was forced to undergo knee surgery due to an injury sustained during the previous campaign.

First-team opportunities proved harder to come by for Clare in 2022 under Lee Radford, making 3 appearances, though he was a part of the coaching staff for the club's academy.