The female in company dealt with an offshore worker (9)
I believe the answer is:
fisherman
'offshore worker' is the definition.
(someone who works at sea)
'the female in company dealt with an' is the wordplay.
'the female' becomes 'she' ('she' refers to a woman).
'in' indicates putting letters inside.
'company dealt with' becomes 'firm' (firm can mean a company or business).
'she' put within 'firm' is 'fisherm'.
'fisherm'+'an'='FISHERMAN'
(Other definitions for fisherman that I've seen before include "One possibly catching sole" , "He's an angler" , "Male anger" , "Fin masher might be all at sea" , "He casts" .)