Muck up is a term used to describe an action that results in something being ruined or spoiled. The crossword solutions for this term include 'BUNGLE' (6 letters), which means to make a mess of something; 'SPOIL' (5 letters), which means to ruin the quality of something; 'ERR' (3 letters), which means to make a mistake; 'BOTCH' (5 letters), which means to do something badly; 'SULLY' (5 letters), which means to damage someone's reputation; 'FLOUNDER' (8 letters), which means to be confused and uncertain; 'MUTILATE' (8 letters), which means to damage something severely; 'STRUGGLE' (8 letters), which means to have difficulty doing something; and 'CONTAMINATE' (11 letters), which means to make something impure.