Length adding to value in clawed animal (5)
I believe the answer is:
ratel
'clawed animal' is the definition.
(ratels are badger-like animals)
'length adding to value' is the wordplay.
'length' becomes 'l' (abbreviation in geometry).
'adding to' says to put letters next to each other.
'value' becomes 'rate' (both can mean to esteem).
'l' put after 'rate' is 'RATEL'.
'in' acts as a link.
(Other definitions for ratel that I've seen before include "Badger-like creature" , "Mammal's" , "predator" , "animal like a badger" , "one wanting honey" .)