The crossword solution for the term 'hammer away at' is 'RAP'. This term is often used to describe a repetitive action, such as hammering a nail into a wall. It can also be used to describe a person or group of people who are working hard and persistently on a task. In this context, 'RAP' is a reference to the musical genre of RAP music, which is characterized by its fast-paced and often repetitive lyrics.