The phrase "let one have it" typically means to attack or criticize someone harshly. Some antonyms for this phrase could include "letting it slide," "being forgiving," or "going easy on someone." These antonyms imply a sense of tolerance and patience rather than hostility and aggression. Other antonyms might include "praise," "encourage," or "support," as these words convey positivity and a willingness to help rather than tear down. Ultimately, the choice of antonym will depend on the context and desired meaning; however, by considering these alternatives, one can convey a more nuanced message and avoid potentially harmful language.