Clark began his career with the youth team of Rangers but was released at 15 and joined Aberdeen. He appeared as an unused substitute during the 2008–09 season and in early 2009, Clark signed a contract extension with the club.
To gain first team experience, Clark joined Peterhead on loan until January. Clark made his debut for the club on 19 September 2009, where he came on as a substitute in the 74th minute as Peterhead drew 1–1 with Arbroath. Clark's loan spell with Peterhead was extended until the end of the 2009–10 season. In the 2009–10 season, Clark would make twenty-five appearances and score four times. Clark, along with Jonathan Crawford, was released by the club after being told they wouldn't be offered a new contract.
After being released by Aberdeen, Clark joined Peterhead permanently in August 2010. Like his loan spell, Clark continued to be a first team regular for the club, where he made twenty-nine appearances and scored four times.
He moved to Queen of the South in July 2011, signing a one-year contract extension in May 2012. The first season with Queen of the South was a struggle for Clark, as he failed to score his first goal, though it eventually happened in the second round of Scottish League Cup against Forfar Athletic.
The 2012–13 season was an improvement and breakthrough season for Clark after his dad, Sandy, joined the club as an assistant manager and he formed a striking partnership with Derek Lyle. Clark would score 41 goals in 46 appearances in all competitions, including scoring two hat-tricks against Stranraer and Forfar Athletic. Clark also played a role in winning the Challenge Cup Final when he scored the opener before Partick Thistle equalised, leading to a penalty shootout. Queen of the South would win the penalty shootout 6–5 to lift the cup. With the club also winning the Second Division, this gained the club their inaugural league and cup double.
Clark was the SFL Division 2 Player of the Year for the 2012–13 season, and he also won the Ginger Boot Award for being the top scorer across all four Scottish divisions. Clark was also named in the PFA Scotland Team of the Year for the Second Division alongside team-mates Chris Mitchell, Mark Durnan, Chris Higgins, Daniel Carmichael and Lee Robinson.
In May 2013 he signed a three-year contract with Rangers, effective from 1 September 2013. The move was successful after Clark started talks with Ally McCoist. Ahead of the 2013–14 season, Clark expressed the opinion that playing in the Scottish League One would not be easy.
Clark scored on his debut on 31 August 2013 after 30 seconds, as Rangers won 5–0 against East Fife, just one day before the end of the club's transfer embargo. After the match, Clark said he believed the club could score 100 goals by the end of the season after scoring 18 goals at such an early stage. Clark initially struggled to make an impact, as he was often on the bench. This led to the Evening Times questioning whether Clark should become a first team starter. This continued until he scored four goals in a 6–1 win over Forfar Athletic on 3 December 2013. In the second half of the season, Clark suffered a broken foot that kept him out for five weeks. After his return, Clark scored in a 2–1 win over Brechin City on 23 March 2014.
On 3 May, Rangers became the first side in 116 years to go an entire league season unbeaten after a 1–1 draw with Dunfermline during which they clinched the Scottish League One championship. On 28 December 2015, Clark scored in the 65th minute in a crucial match against Hibernian, which put Rangers three points clear of Hibs.
On 23 May 2016, Clark was released by Rangers.
On 25 June 2016, Clark signed for Football League One side Bury on a two-year deal. Clark made his debut for Bury in a 2–0 victory over Charlton on 6 August 2016. However, after Bury signed James Vaughan from Birmingham City, Clark was deemed surplus to requirement and allowed to leave Gigg Lane, having made only 4 competitive appearances.
Clark returned to Scotland after 2 months in England, signing for Scottish Championship side Dunfermline Athletic in August 2016 on a two-year deal. His move to the Pars saw Clark team up with his former manager at Queen of the South, Allan Johnston, as well as his father Sandy Clark who was also assistant to Johnston at the Doonhamers.
Clark was born in Bellshill, Scotland; his father is a former footballer, Sandy. While growing up, Clark once participated in the half-time entertainment during a pre-season friendly clash with Everton in 2003.As of 18 September 2017
Queen of the SouthScottish Challenge Cup: 2012–13
Scottish Second Division: 2012–13
Scottish League One: 2013–14
Scottish Championship: 2015–16
Scottish Challenge Cup: 2015–16