Completely consumes American and 7 drink (4,2)
I believe the answer is:
uses up
'completely consumes' is the definition.
'uses up' can be an answer for 'consumes' ('use up' can be a synonym of 'consume'). I'm not sure about the 'completely' bit.
'american and 7 drink' is the wordplay.
'american' becomes 'us'.
'and' is a charade indicator (letters next to each other).
'7' becomes 'e' (I can't justify this - if you can you should give a lot more credence to this answer).
'drink' becomes 'sup' (I've seen this before).
'us'+'e'+'sup'='USES UP'
Can you help me to learn more?
(Other definitions for uses up that I've seen before include "'Depletes (4,2)'" , "Exhausts" , "Consumes" , "drains" .)