Mythical equine (7)
I believe the answer is:
unicorn
'mythical equine' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for unicorn that I've seen before include "Representative of Scotland" , "Animal of fable" , "Mythical white equine" , "Mythical and heraldic beast" , "Animal rumoured" .)