KGB's land (4)
I believe the answer is:
ussr
'kgb's land' 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 union of socialist republics" , "In brief, former Soviet federation" , "Former association of communist republics" , "The Beatles? song 'Back in the . . . .'" , "Former federation of Russial and other states" .)