The term 'use elbow grease' is a phrase used to describe the effort required to do a job properly. In this case, it can be used to describe the effort needed to clean something thoroughly. The crossword solutions for this phrase are 'SCOUR' and 'SCRUB'. Scouring involves using an abrasive material to remove dirt and grime from a surface, while scrubbing involves using a brush or cloth to remove dirt and grime. Both of these methods require a lot of effort and elbow grease to get the job done properly.