It could mean rain in an Asian republic (8)
I believe the answer is:
armenian
'an asian republic' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'it could mean rain' is the wordplay.
'mean rain' anagrams to 'ARMENIAN'.
Though, I am not sure how this is indicated.
'in' is the link.
Can you help me to learn more?
(Other definitions for armenian that I've seen before include "of the Southern Caucasus" , "language" , "ethnic group in Asia" , "Person from Yerevan, say" , "Eg, native of Yerevan" .)