Run down/out the clock
Definition 1 of 2
Pro Tip 1/3Sports Origin
Originally from sports, used when a team tries to preserve a lead by holding onto the ball. 
After scoring, the football team would run down the clock to end the match.
Pro Tip 2/3Strategy Implication
Implies a strategic choice to waste time, often viewed negatively by those waiting. 
The student tried to run out the clock during the exam, avoiding the hard questions.
Pro Tip 3/3Tension Builder
Can create suspense or frustration for the audience anticipating the game's outcome. 
The audience was on edge as the team kept running down the clock.