Aware of two men down (7)
I believe the answer is:
knowing
'aware of' is the definition.
(I've seen this before)
'two men down' is the wordplay.
'two men' can mean two substitutions for 'man'.
'man' becomes 'k' (abbreviation for king, a chess man).
'man' becomes 'n' (knight, a man in chess).
'down' becomes 'owing' (e.g. money).
'k'+'n'+'owing'='KNOWING'
(Other definitions for knowing that I've seen before include "Fly" , "State of awareness" , "Experienced; intelligent" , "Meaningful" , "Cunning" .)