Fix what you and me mount for hero (7)

I believe the answer is:
pegasus
'mount for hero' is the definition.
The definition and answer can be both natural objects as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'fix what you and me' is the wordplay.
'fix' becomes 'peg' (to fix or attach with a peg).
'what' becomes 'as' (I can't justify this - if you can you should give a lot more credence to this answer).
'you and me' becomes 'us' (the two of us).
'peg'+'as'+'us'='PEGASUS'
Can you help me to learn more?
(Other definitions for pegasus that I've seen before include "high horse" , "Northern hemisphere constellation - use gaps (anag)" , "fabulous horse" , "Exceptional horse" , "Winged horse of Greek myth" .)
