Highlands hillsides (5)
I believe the answer is:
braes
'highlands hillsides' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for braes that I've seen before include "Sabre (anag) - Scottish banks" , "Scottish hillsides, banks" , "Old song 'By yon bonny banks, and by yon bonny . . . . .'" , "Hillsides in Scotland" .)