Pipsqueak cat for every fish (14)
I believe the answer is:
whippersnapper
'pipsqueak' is the definition.
(I've seen this before)
'cat for every fish' is the wordplay.
'cat' becomes 'whip' (cat o' nine tails or cat is a type of whip).
'for every' becomes 'per' ('per' means 'for each' or 'for every').
'fish' becomes 'snapper' (snapper is a kind of fish).
'whip'+'per'+'snapper'='WHIPPERSNAPPER'
(Other definitions for whippersnapper that I've seen before include "Impudent lad" , "Pipsqueak" , "brash youngster" , "Cheeky youngster" , "Presumptuous young person" .)