Disputed region in mid-Balkans with a quiet border to the west (7)
I believe the answer is:
kashmir
'disputed region' is the definition.
'balkans with a quiet border to the west' is the wordplay.
'balkans with' becomes 'ka' (I can't justify this - if you can you should believe this answer much more).
'a quiet' becomes 'sh'.
'border' becomes 'rim' (I've seen this before).
'to the west' shows that the letters should be reversed in order.
'rim' backwards is 'mir'.
'ka'+'sh'+'mir'='KASHMIR'
'in mid' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
(Other definitions for kashmir that I've seen before include "disputed region of Asia" , "Disputed Asian territory" , "Region on the border of India and Pakistan" , "Himalayan region" , "Region claimed by both India and Pakistan" .)