It adjoins Afghanistan in Risk (4)
I believe the answer is:
ural
'it adjoins afghanistan in risk' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ural that I've seen before include "River of central Russia" , "River feeding Caspian Sea" , "Mountain range between Europe and Asia" , "Russian river giving name to mountains" , "The .... Mountains divide Europe and Asia" .)