Winged horse of Greek myth (7)
I believe the answer is:
pegasus
'winged horse of greek myth' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for pegasus that I've seen before include "with a place in the firmament" , "group of stars" , "Winged horse - constellation" , "Northern hemisphere constellation - use gaps (anag)" , "Flier" .)