Employ a hearty couple until exhausted (3,2)
I believe the answer is:
use up
'employ' is the definition.
(thesaurus)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for use up that I've seen before include "Finish, exhaust" , "Expend" , "Completely consume" , "Exhaust (resources)" , "Consume (stocks)" .)