Domestic animal (3)
I believe the answer is:
pet
'domestic animal' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for pet that I've seen before include "Favourite, perhaps a domestic animal" , "Favourite; fit of the sulks" , "Darling; fit of sulks" , "Bad humour; darling" , "Favourite pupil" .)