Copy in Home Counties writer (6)
I believe the answer is:
scribe
'writer' is the definition.
(scribe is a kind of writer)
'copy in home counties' is the wordplay.
'copy' becomes 'crib' (crib can mean to copy from another source).
'in' indicates putting letters inside.
'home counties' becomes 'SE' (the Home Counties are in the South East of England).
'crib' placed into 'se' is 'SCRIBE'.
(Other definitions for scribe that I've seen before include "Clerk, a public copyist" , "One writing documents" , "Medieval clerk" , "Former document copier" , "Professional writer" .)