Sailor employed and mistreated (6)
I believe the answer is:
abused
'mistreated' is the definition.
(synonyms)
'sailor employed' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'employed' becomes 'used' ('use' can be a synonym of 'employ').
'ab'+'used'='ABUSED'
'and' is the link.
(Other definitions for abused that I've seen before include "Reviled, or used wrongly like drugs" , "Swore at" , "Took undue advantage of" , "Criminally maltreated" , "Offended" .)