The term 'apply, as elbow grease' can be summarized as exerting effort to achieve a desired result. This phrase is often used to describe the need for hard work and dedication in order to accomplish a task. The crossword solution for this term is 'EXERT, ' which means to put forth effort or energy. Therefore, the phrase 'apply, as elbow grease' is a metaphor for putting in the necessary effort to achieve a goal.