Rain is unusual in this country (4)
I believe the answer is:
iran
'this country' is the definition.
(Iran is an example)
'rain is unusual' is the wordplay.
'is unusual' indicates an anagram.
'rain' with letters rearranged gives 'IRAN'.
'in' is the link.
(Other definitions for iran that I've seen before include "Modern-day Persia" , "Rain (anag) - country" , "Country where the official language is Farsi" , "Iraq's neighbour" , "Country lying to south of Caspian sea" .)