The term 'Act on Behalf Of' can be summarized by three crossword solutions: REPRESENT (9 letters), DEPUTISE (8 letters), and ATTORNEY (8 letters). REPRESENT is a verb meaning to stand in for someone else, often in a professional capacity. DEPUTISE is a verb meaning to act as a deputy or substitute for someone else. ATTORNEY is a noun referring to a lawyer or legal representative. All three terms refer to the idea of acting on behalf of someone else, either in a professional or legal capacity.