Afghanistan neighbor (4)
I believe the answer is:
iran
'afghanistan neighbor' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for iran that I've seen before include "Persia some time ago" , "Tehran's country" , "Modern name for Persia" , "Modern Persia (4)" , "Country where ayatollahs replaced a shah" .)