The term 'JACK WHO WOULD EAT NO FAT' is a reference to the nursery rhyme 'Jack SPRAT'. Jack SPRAT was a character in the English nursery rhyme who could eat no fat and his wife could eat no lean. The rhyme is about how the couple had different eating habits, with Jack eating only lean food and his wife eating only fatty food. The crossword solution for this term is 'SPRAT', which is the last name of the character in the nursery rhyme.