High Scottish mountain (5)
I believe the answer is:
munro
'high scottish mountain' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for munro that I've seen before include "Scottish mountain over three-thousand feet" , "One of the Scottish peaks over 3000 feet" , "H H ---, the author 'Saki'" , "One of Scottish mountains over 3000 feet" , "Big Ben" .)