Scottish mountain (3)
I believe the answer is:
ben
'scottish mountain' is the definition.
(Scottish term for a peak, eg Ben Nevis)
This is all the clue.
(Other definitions for ben that I've seen before include "Boy for a Scottish mountain" , "inner room in Oban, say" , "A Big London clock tower" , "Big . . . is a famous London clock-tower" , "Mountain peak (Scot.)" .)