Consumes; exhausts (4,2)
I believe the answer is:
uses up
This clue is a double definition.
'consumes' is the first definition.
('use up' can be a synonym of 'consume')
'exhausts' is the second definition.
('use up' can be a synonym of 'exhaust')
(Other definitions for uses up that I've seen before include "Consumes" , "'Depletes (4,2)'" , "drains" , "Exhausts" .)