Fire-breathing Greek monster (7)
I believe the answer is:
chimera
'fire-breathing greek monster' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for chimera that I've seen before include "Mythical monster, part lion, goat and serpent" , "Creature such as a gryphon" , "fabulous creature" , "phantom" , "Wild notion" .)