The phrase "cleaned one's act" implies a significant change in behavior, often associated with the cessation of bad habits or negative actions. Antonyms for this phrase would include terms such as "backslid," "relapsed," or "regressed." These words suggest a return to previous, negative behaviors, indicating that the individual may have been unable to maintain positive changes in their behavior over time. Other antonyms for "cleaned one's act" may include "maintained a negative demeanor," "remained stagnant," or "lapsed into old habits." These phrases all suggest that the individual in question has not made positive changes to their behavior and may be stuck in a pattern of negativity.
