Companion from different sector (6)
I believe the answer is:
escort
'companion' is the definition.
(escort is a kind of companion)
'different sector' is the wordplay.
'different' is an anagram indicator.
'sector' anagrammed gives 'ESCORT'.
'from' is the link.
(Other definitions for escort that I've seen before include "giving protection" , "Accompany, chaperon" , "Provide company - car - guard" , "Armed guards" , "17 [DESTROYER]" .)