Jockey’s mount (5)
I believe the answer is:
horse
'jockey's mount' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for horse that I've seen before include "it can become addictive" , "Shore (anag)" , "Vaulting --; -- sense" , "punch, perhaps" , "Domesticated animal" .)