It's in Home Counties locale (4)
I believe the answer is:
site
'locale' is the definition.
(I've seen this before)
'it's in home counties' is the wordplay.
'it's' becomes 'it' (I've seen this in other clues**).
'in' is an insertion indicator.
'home counties' becomes 'se'.
'it' put inside 'se' is 'SITE'.
(Other definitions for site that I've seen before include "Somewhere to build, perhaps" , "Building land" , "Location or piece of land" , "Location (of building, dig etc)" , "Ties into building location" .)