From Longman Dictionary of Contemporary Englishstart/stop the clockstart/stop the clockTMCto start or stop measuring how much time is left in a game or sport that has a time limit → clock
Examples from the Corpus
start/stop the clock• The clock is stopped when a player runs out of bounds with the ball.• If you are bled totally dry and white, they will simply stop the clock.• Some expend tremendous energy desperately trying to stop the clock.• You start the clock, paint the glue, fit the pieces, block the cramps. 