Certain agent's area (6)
I believe the answer is:
realty
'certain agent's area' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for realty that I've seen before include "Property ownership in the US" , "Property legally" , "Lyrate (anag.)" , "American real estate" , "Immovable property" .)