Farsi-speaking country (4)
I believe the answer is:
iran
'farsi-speaking country' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for iran that I've seen before include "Rain (anag) - country" , "Middle East country" , "Previously known as Persia" , "Country where ayatollahs replaced a shah" , "Iraq's neighbour" .)