Medusa's hair (6)
I believe the answer is:
snakes
'medusa's hair' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for snakes that I've seen before include "Legless reptiles" , "Rattlers, asps, cobras etc" , "Limbless reptiles" , "[CREES]" , "Go down them on board" .)