Risk territory that borders Siberia (4)
I believe the answer is:
ural
'risk territory that borders siberia' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ural that I've seen before include "Europe/Asia river" , "Russian river giving name to mountains" , "Russian river giving name to mountain range" , "River of central Russia" , "Mountains in Russia" .)