Wrongful waste of labour? (5)
I believe the answer is:
sweat
'labour' is the definition.
(I know that sweat is a type of labour)
'wrongful waste' is the wordplay.
'wrongful' indicates an anagram (I've seen this in other clues).
'waste' anagrammed gives 'SWEAT'.
'of' acts as a link.
(Other definitions for sweat that I've seen before include "Toil" , "(Of argument) intense" , "Male perspiration?" , "Perspire" , "Trouble in Australia" .)