Fire-breather (6)
I believe the answer is:
dragon
'fire-breather' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for dragon that I've seen before include "Fire breathing mythological creature" , "chased by addicts" , "St George's slew one" , "Teutonic mythological creature" , "Monster - type of fly" .)