Climbed peak in Scotland, then roughly showed the way (6)
I believe the answer is:
scaled
'climbed' is the definition.
(scaling is a kind of climbing)
'peak in scotland then roughly showed the way' is the wordplay.
'peak in' indicates taking the first letters (in a down clue, the letter at the top of the word).
'then' is a charade indicator (letters next to each other).
'roughly' becomes 'ca' (abbreviation for circa).
'showed the way' becomes 'led' (lead can mean to show someone the way).
The initial letter of 'scotland' is 's'.
's'+'ca'+'led'='SCALED'
(Other definitions for scaled that I've seen before include "like fish or reptile" , "Surmounted" , "Weighed" , "Climbed - peeled off" , "like a snake" .)