The term 'USE ELBOW GREASE ON' is a phrase used to describe the act of using physical effort to clean something. The two crossword solutions for this term are 'SCRUB' and 'SCOUR'. Scrubbing is the act of using a brush or other abrasive material to remove dirt and grime from a surface, while scouring is the act of using a chemical cleaner to remove dirt and grime. Both of these methods require physical effort and elbow grease to be effective.