Employed American press chief (4)
I believe the answer is:
used
'employed' is the definition.
('use' can be a synonym of 'employ')
'american press chief' is the wordplay.
'american' becomes 'us' (abbreviation for United States).
'press chief' becomes 'ed' (I've seen this in other clues).
'us'+'ed'='USED'
(Other definitions for used that I've seen before include "Pre-loved" , "with some traffic" , "Went through" , "like majority of cars?" , "Second-hand; exploited" .)