Exhaust American power restraining Brussels? (3,2)
I believe the answer is:
use up
'exhaust' is the definition.
(I know that exhaust can be written as use up)
'american power restraining brussels?' is the wordplay.
'american' becomes 'US' (United States).
'power' becomes 'p' (symbol in physics).
'restraining' is an insertion indicator.
'brussels?' becomes 'EU' (European Parliament is based in Brussels).
'us'+'p'='usp'
'usp' going around 'eu' is 'USE UP'.
(Other definitions for use up that I've seen before include "Consume (stocks)" , "Entirely consume" , "Finish, exhaust" , "Expend" , "Exhaust (resources)" .)