Cold War adversary (4)
I believe the answer is:
ussr
'cold war adversary' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ussr that I've seen before include "Former federation of Russial and other states" , "Country established in1922 and dissolved in 1991, in short" , "Former Soviet Union" , "Country established in 1922 and dissolved in 1991, in short" , "Former union of socialist republics" .)