The term 'HARD TO CLEAN UP' can be summarized by the crossword solution of 'MESSY', which implies that it is difficult to clean up. This could refer to a physical mess, such as spilled food or a broken object, or it could refer to a figurative mess, such as a complicated situation or a difficult problem. In either case, the implication is that it will take a lot of effort and time to clean up the mess.