Country bordering the Caspian sea (4)
I believe the answer is:
iran
'country bordering the caspian sea' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for iran that I've seen before include "bombless state" , "Persia some time ago" , "Middle East Islamic republic" , "Tehran's country" , "Middle East country" .)