Answer: flaresup

AnswerCrossword Clue
FLARESUPSuddenly intensifies
FLARESUPCatches fire
FLARESUPBursts into flames
FLARESUPGets angry
FLARESUPFlies off the handle.
FLARESUPFlies off the handle
FLARESUPComes back, in a way
FLARESUPIntensifies