The term 'beat a dead horse' is an idiom that means to continue doing something that has already been done to the point of exhaustion. The two crossword solutions for this term are 'BELABOR' (7 letters) and 'OVERDO' (6 letters). BELABOR means to discuss or explain something at length, often in an effort to persuade someone. OVERDO means to do something to excess or to an extreme degree. Both words can be used to describe the act of beating a dead horse, as they both imply going beyond what is necessary or appropriate.