Animal partial to molasses (3)
I believe the answer is:
ass
'animal' is the definition.
(term for a donkey)
'partial to molasses' is the wordplay.
'partial to' indicates the answer is hidden within the clue (the answer forms part of the clue).
'ASS' is hidden in the letters of 'molasses'.
(Other definitions for ass that I've seen before include "Clot" , "Blockhead" , "animal inside" , "An American backside" , "Donkey or foolish person" .)