Heraldic dragon (6)
I believe the answer is:
wyvern
'heraldic dragon' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for wyvern that I've seen before include "Heraldic dragon with two legs and two wings" , "Dragon with wings in medieval heraldry" , "In heraldry, a dragon with wings, two legs and a barbed tail" , "Heraldic form of dragon" , "Fire-breathing dragon with a snake's tail" .)