Snake-haired Gorgon (6)
I believe the answer is:
medusa
'snake-haired gorgon' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for medusa that I've seen before include "Monster" , "Hideous female" , "Gorgon killed by Perseus - jellyfish" , "Petrifying woman" , "One of three sisters with snakes for hair" .)