Flash in the pan is an idiom that refers to something that is initially successful but quickly fades away. It is derived from the old practice of firing a gun, or 'flashing in the pan, ' which would produce a spark but no bullet. The term is often used to describe a person or thing that has a brief moment of success but then quickly disappears. The crossword solution for this term is FAD, which stands for 'FAD' or 'fashionable trend.' A FAD is a short-lived trend that quickly becomes popular and then fades away just as quickly.