Setter, perhaps, is good after party (3)
I believe the answer is:
dog
'setter perhaps' is the definition.
(setter is a kind of dog)
'good after party' is the wordplay.
'good' becomes 'g' (abbreviation).
'after' means one lot of letters go next to another.
'party' becomes 'do' (do is a kind of party).
'g' after 'do' is 'DOG'.
'is' is the link.
(Other definitions for dog that I've seen before include "Follow closely; animal" , "Shadow" , "Worry" , "Follow; pet" , "Sort of collar, fight, days" .)