He represented Great Britain over 5000 metres at the 1983 World Championships in Athletics and the 1981 Summer Universiade.

[3] Clarke was a three-time silver medallist at the competition (1982, 1987, 1989) and also won a team bronze in 1992, sharing the honours with Mike McLeod, Hugh Jones, Julian Goater, Steve Kenyon, Karl Harrison, Carl Thackery, Kevin Forster, Steve Binns, Tim Hutchings, Gary Staines, Richard Nerurkar, and Eamonn Martin, among others.

Professionally, he worked as a labourer and hospital porter before becoming a history and physical education teacher.

[9] He shares the British record in the ekiden marathon relay, alongside Carl Thackery, Jon Solly, Mark Scrutton, and Karl Harrison, with a silver medal-winning time of 1:59:14 hours set at the 1986 IAAF World Challenge Road Relay.

[3] He continues to take part in the sport as a masters athlete, mostly in local parkruns, though he completed the 2016 London Marathon in 3:03:54 hours.