Clarke has Indigenous Australian heritage and his ancestry can be traced to the Gambalang people of the Daly River region of the Northern Territory.

Clarke's brother Raphael was also drafted by St Kilda, as Clarke played 57 games during his first three seasons, taking over the number 3 guernsey from former St Kilda captain Nathan Burke when Burke retired at the end of the 2003 AFL season.

In 2005 Clarke he struggled in form and his season ended early when he injured his hamstring in Round 17 against Collingwood.

In 2011, Clarke almost completed a full preseason when he ruptured his anterior cruciate ligament in his right knee[2] and, although offered a rookie list position by Brisbane, retired from football at the end of the 2011 season.

[5] Clarke has also worked with the AFL and the AFL Players Association (AFLPA) in Indigenous engagement and was a founding director of the Unity Foundation which worked to provide housing and support for homeless Indigenous youth.