The crossword solution for the term 'Rat Fink' is 'STOOLIE', which is a seven-letter word. STOOLIE is a slang term for an informant or someone who gives information to the police or other authorities. It is often used to describe someone who has betrayed their friends or family by providing information to the authorities. Rat Fink is a derogatory term used to describe someone who has betrayed their friends or family.