Guard different sector (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
escort
'guard' is the definition.
(I know that escort is a type of security guard)
'different sector' is the wordplay.
'different' is an anagram indicator (letters placed in a different order).
'sector' anagrammed gives 'ESCORT'.
(Other definitions for escort that I've seen before include "Accompany (a person)" , "Bodyguard" , "'Accompany, perhaps protectively (6)'" , "attendance" , "Entourage" .)