Meaning:

Work or do something very fast to finish it before a deadline

If you have a situation in which you have to finish doing something very quickly by a deadline, you call that situation a race against the clock / time.

Example:

They started a race against the clock to finish the interior of the new store that was scheduled to open in a month.

The engineers worked 15 hours a day to complete the new computer system by the deadline. It was really a race against time.

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