Young setter, say, boxing pound for pound (4)
I believe the answer is:
pulp
'for pound' is the definition.
(thesaurus)
'young setter say boxing pound' is the wordplay.
I cannot quite see how this works, but
'pound' could be 'l' (abbreviation e.g. Lsd - pounds, shillings, pence) and 'l' is located in the answer.
'young' could be 'pup' (pup is a kind of young) and 'pup' is present in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for pulp that I've seen before include "Mush" , "recycle paper" , "Soft, soggy mass" , "Crush" , "Soft fleshy part of a fruit" .)