Country river - a Russian river (5)
I believe the answer is:
rural
'country' is the definition.
(I know that country can be written as rural)
'river a russian river' is the wordplay.
'river' becomes 'r' (abbreviation for river).
'a russian river' becomes 'ural' (I've seen this in another clue).
'r'+'ural'='RURAL'
(Other definitions for rural that I've seen before include "Countrified" , "Bucolic; pastoral" , "Sort of dean" , "living in the countryside" , "Pastoral or agricultural" .)