He qualified for the first time for the 2020 World Snooker Championship, defeating Mark Allen 10–8 in the first round despite Allen scoring 5 centuries. Clarke was involved in a controversial incident during his second round match against Anthony McGill. Clarke was leading 7–2 when McGill complained to him directly that he had stood in his eyeline on several different occasions during the match while he was getting down on a shot. Referee Jan Verhaas intervened but it seemed to unsettle Clarke after he won the frame. During the interval he tweeted 'You want to dance, let's dance.' McGill won the remaining five frames of the session to trail 7–8. Ultimately the match went to a decider; Clarke was in first during the deciding frame before failing to escape from a snooker, and leaving a free ball. This was enough for McGill to win the match and see Clarke lose 12–13.