When someone is working against the clock, they are racing against time to finish a task or meet a deadline. There are a variety of synonyms that can be used to convey a similar sense of urgency, including "under pressure," "in a hurry," "pressed for time," "against time," "chasing deadlines," and "time crunch." These phrases all evoke the feeling of being up against a tight deadline, with little time to spare. Whether you're working on a project at work or studying for an upcoming exam, these synonyms can help you describe the frantic pace at which you're working to get everything done in time.