Exploited American editor (4)
I believe the answer is:
used
'exploited' is the definition.
(synonyms)
'american editor' is the wordplay.
'american' becomes 'US' (United States).
'editor' becomes 'ed' (abbreviation).
'us'+'ed'='USED'
(Other definitions for used that I've seen before include "Took advantage of" , "took a chance on becoming dependent" , "taken advantage of!" , "Pre-owned" , "Utilised" .)