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' says to hollow out the word (remove centre letters) (outsides of).
'following' says to put letters next to each other.
'party' becomes 'do' (do can informally mean a party).
'gangs' with its middle 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" .)