Highlands hillside (4)
I believe the answer is:
brae
'highlands hillside' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for brae that I've seen before include "Bank of Scotland" , "Steep Scots hillside" , "Bare on Scottish hillside" , "Upland area in Scotland" , "bank on Clydeside" .)