Cat found in a pound (5)
I believe the answer is:
ounce
This clue is a double definition.
'cat' is the first definition.
(ounce is a kind of cat)
'a pound' is the second definition.
(thesaurus)
'found in' is the link.
(Other definitions for ounce that I've seen before include "A little bit" , "There are quite a few in the pound" , "Approx. twenty-eight gm" , "Wildcat" , "Imperial unit of weight" .)