The proverb "against the clock" means to work in a great hurry and with great urgency to finish something before a deadline, while also emphasizing the limited time that is available.
Against the clock is a situation in which you race against time to complete a project or a task, which creates a sense of pressure and the need to act very quickly.
Meeting a deadline is the core meaning of "against the clock" or "working against the clock" which revolves around the idea of a set time limit and the effort to complete something before the limit expires.
The idiom of "against the clock" also highlights the pressure and the haste that is involved in trying to beat the deadline.
And racing against time implies a feeling of struggling or racing against the remaining time to achieve a goal.
Examples of "against the clock" or "working against the clock" are a team that is working late to complete a project or emergency services working fast to save someone's life.
In essence, "against the clock" captures the feeling of having to work as quickly and efficiently as you can to succeed before a certain time runs out.
If you do something against the clock, you do the thing as fast as possible and try to finish it before the time runs out.