Like multiple Olympic champion Usain Bolt and former Jamaican sprinter Michael Green, Clarke is a former student of William Knibb Memorial High School.

[1] His first international appearance for Jamaica came at the 2002 NACAC Under-25 Championships in Athletics, where he led off the Jamaican 4×100 metres relay team to take the bronze medal.

[2] He set a personal best of 10.24 seconds at the 2005 Central American and Caribbean Championships in Athletics, coming sixth in the 100 m final and was also part of the relay team which finished in fifth place.

[10] He was selected as a first heat relay runner at the 2009 World Championships in Athletics and received a gold medal as the Jamaican quartet went on to win the title.

[13] He ran two sub-10-second times at the Doha Athletic Grand Prix, albeit wind-assisted and was a regular competitor on the 2010 IAAF Diamond League circuit.

[15] At the 2012 Birmingham Indoor Grand Prix he caused an upset by defeating both Asafa Powell and Nesta Carter over 60 m as he ran a Jamaican record time of 6.47 seconds to win the race.