Medic terminated farm worker (6)
I believe the answer is:
drover
'farm worker' is the definition.
'medic terminated' is the wordplay.
'medic' becomes 'dr'.
'terminated' becomes 'over' ('over' can be a synonym of 'terminated').
'dr'+'over'='DROVER'
(Other definitions for drover that I've seen before include "One driving flock to market" , "I bring along many animals" , "Herdsman" , "Person moving sheep or cattle from one place to another" , "Man who herds cattle" .)