It's hard work sorting waste (5)
I believe the answer is:
'it's hard work' is the definition.
'sorting waste' is the wordplay.
'waste' can be anagrammed to 'SWEAT'.
But, I am not clear how this is indicated.
Can you help me to learn more?
(Other definitions for sweat that I've seen before include "It's hard work" , "Salty fluid secreted by the body" , "(Of argument) intense" , "Male perspiration?" , "Soldier" .)