Exploited American newspaper employee? (4)

I believe the answer is:
used
'exploited' is the definition.
(synonyms)
'american newspaper employee?' is the wordplay.
'american' becomes 'US' (United States).
'newspaper employee?' becomes 'ed' (I can't explain this - if you can you should believe this answer much more).
'us'+'ed'='USED'
Can you help me to learn more?
(Other definitions for used that I've seen before include "Scottish expert" , "Prepossessed, perhaps" , "Second-hand - not wasted" , "with some traffic" , "Subject to exploitation" .)
