Beat the clock
Definition 1 of 2
Pro Tip 1/3Urgency
Conveys a sense of urgency, acting fast to achieve a goal within a limited time. 
She worked quickly to beat the clock and submit her application.
Pro Tip 2/3Idiomatic
Often used in everyday English to describe quick completion of tasks. 
He managed to beat the clock and get to the post office before it closed.
Pro Tip 3/3Success
Implies successful completion, not just participation or effort. 
They beat the clock, finishing the project before the deadline.