Exhausted American fool ultimately promoted (4,2)
I believe the answer is:
used up
'exhausted' is the definition.
('use up' can be a synonym of 'exhaust')
'american fool ultimately promoted' is the wordplay.
'american' becomes 'US' (abbreviation for United States).
'fool ultimately' becomes 'ed' (I can't justify this - if you can you should believe this answer much more).
'promoted' becomes 'up' (moving up).
'us'+'ed'+'up'='USED-UP'
Can you help me to learn more?
(Other definitions for used up that I've seen before include "Consumed completely" , "Spent" , "Exhausted the supply" , "Consumed, finished" .)