The crossword solution for the term MESS (WITH), AS A LOCK is TAMPER. Tampering is the act of interfering with something in order to alter its function or make it work improperly. It is often done maliciously, such as when someone tampers with a lock in order to gain access to a restricted area. Tampering can also be done accidentally, such as when someone inadvertently messes with a lock and causes it to malfunction.