The term 'grant-in-AID' is a type of financial assistance given by a government or other organization to an individual or group. It is usually given in the form of a grant, which is a sum of money given without any expectation of repayment. The three-letter solution for this crossword is AID, which stands for Assistance In Development. Grant-in-aids are typically used to help fund projects or initiatives that are deemed to be of public benefit.