The phrase "gave leg up" is often used to describe a situation where someone helps another person by providing support or assistance. Antonyms for this phrase would include phrases such as "denied assistance," "refused aid," or "abandoned." These antonyms convey a sense of withholding support or leaving someone on their own to struggle. Other potential antonyms might include phrases such as "acted against," "hindered progress," or "imposed obstacles," all of which suggest actively working against someone's interests. While "gave leg up" implies a positive action taken to support someone else, its antonyms suggest a negative or harmful approach.