Case of gangs following party animals (4)
I believe the answer is:
dogs
'animals' is the definition.
The answer is an example.
'case of gangs following party' is the wordplay.
'case of' means to remove the middle letters (like emptying a case).
'following' means one lot of letters go next to another.
'party' becomes 'do' (do can informally mean a party).
'gangs' with its centre taken out is 'gs'.
'gs' after 'do' is 'DOGS'.
(Other definitions for dogs that I've seen before include "eg 27 terriers" , "Persistently follows" , "pets" , "Setters, for example" , "Hounds" .)