Place of exile, yes, for a Soviet head of secret police (7)
I believe the answer is:
siberia
'place of exile' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for siberia that I've seen before include "chosen by Putin for no-frills travel?" , "Former place of exile for a Russian" , "Russian far-east" , "Area of eastern Russia" , "'Region of Russia, famous for its long, cold winters (7)'" .)