Cool set, crazy cats! (7)
I believe the answer is:
ocelots
'cats' is the definition.
(ocelot is a kind of cat)
'cool set crazy' is the wordplay.
'crazy' is an anagram indicator.
'cool'+'set'='coolset'
'coolset' with letters rearranged gives 'OCELOTS'.
(Other definitions for ocelots that I've seen before include "Small leopards found in sole cot" , "Close to, oddly, the wildcats" , "animals in the wild" , "Cats - cool set (anag)" .)