Proper charge (3)
I believe the answer is:
due
I believe this clue is a double definition.
'proper' is the first definition.
(what is due is what is proper or appropriate)
'charge' is the second definition.
(due is a kind of charge)
(Other definitions for due that I've seen before include "Appropriate - fee - now owing" , "Payable; deserved" , "Owed as a debt" , "Expected; proper" , "Proper, appropriate" .)