There are several antonyms for the term "clean up on," which typically means to make a lot of money or be very successful. For example, ones may say "fall behind" or "lose out" instead to indicate a lack of success or financial gain. Other antonyms include "fail," "miss the mark," "struggle," or "underperform." Alternatively, some people may use more colloquial terms such as "bomb," "flop," or "tank" to describe the opposite of cleaning up. Regardless of the term used, it represents a lack of success or financial gain, which is the opposite of what is meant by cleaning up on something.