As a youth, Clarkson played in the 1998 Quebec International Pee-Wee Hockey Tournament with the Toronto Marlborosminor ice hockey team. Following his junior ice hockey career, Clarkson went undrafted and was signed as a free agent by the New Jersey Devils on August 12, 2005. He was assigned to the Albany River Rats of the American Hockey Leaguein September of that year. He would go on to play the majority of the 2006–07 season with the Devils' new minor league team, the Lowell Devils, before receiving a late-season call-up to New Jersey. Clarkson made his NHL debut on March 15, 2007, away against the Carolina Hurricanes. He scored his first NHL goal one game later in a 7–2 loss to Carolina. He would go on to finish the season with New Jersey, including three playoff games, and start the next season in the NHL. Clarkson played in the YoungStars Game during the 56th NHL All-Star Game SuperSkills Competition, scoring one goal and two assists. He was the lone Devils' representative at the festivities, as Martin Brodeur was unable to participate. Clarkson ranked seventh in the NHL in penalty minutes during the 2007–08 season. On July 1, as a restricted free agent, Clarkson was re-signed by the Devils for two years at $800,000 per year. As the 2012–13 NHL lockout began, Clarkson signed with Austrian team EC Red Bull Salzburg to begin the 2012–13 season. Once the NHL lock-out was settled, he returned to the Devils and did well offensively, scoring 15 points in 12 games before slumping and only recording another nine points in the remaining 36 games as New Jersey failed to the make the playoffs. An unrestricted free agent, Clarkson did not re-sign with the Devils during the off-season, instead signing a seven-year, $36.75 million contract with the Toronto Maple Leafs on July 5, 2013. On September 22, 2013, a brawl erupted during a pre-season game against the Buffalo Sabres during which Clarkson left the bench to fight. He subsequently received an automatic ten-game suspension from the NHL. Clarkson ended his first season in Toronto with 5 goals and 11 points in 60 games. In the midst of his second season with the Maple Leafs in the 2014–15 season, and unable to establish a level of play to match his contract, Clarkson was traded by Toronto to the Columbus Blue Jackets in exchange for Nathan Horton on February 26, 2015. Healthy scratches and injuries would hold Clarkson to only 26 games with the Blue Jackets over the next year and a half. As training camp for the 2016–17 season approached, it was announced that Clarkson had failed a physical and would not be invited to practice with the Blue Jackets. He was placed on the long-term injured reserve and ruled out for the entirety of the season, unofficially retiring from playing professionally. On June 21, 2017, Clarkson's contract was obtained by the Vegas Golden Knights at the 2017 NHL Expansion Draft in a pre-arranged trade with the Blue Jackets in order for the Golden Knights to select William Karlsson. On July 23, 2019, Clarkson was traded back to the Maple Leafs in exchange for goaltender Garret Sparks.
Personal life
Clarkson was born in Etobicoke, Ontario, growing up in the Mimico neighbourhood. He and his wife Brittney have five children, three daughters and two sons. The family resides in Castle Pines, Colorado. Clarkson initially served as an assistant coach for the Upper Arlington High School hockey team, before taking on the head coaching job the following year from 2017.
