Catch fire is a phrase that is used to describe something that has suddenly become very popular or successful. The term can also be used to describe an object that has been set alight. In the context of this crossword, the solutions IGNITE, KINDLE and BURN all refer to the act of setting something on fire. IGNITE and KINDLE both mean to start a fire, while BURN means to be consumed by fire. All three words can be used to describe the phrase catch fire.