Of Swiss mountains (6)
I believe the answer is:
alpine
'of swiss mountains' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for alpine that I've seen before include "Relating to a European mountain range" , "Plant of high mountains" , "Native growing up in mountainous area" , "To do with great European mountains" , "Nepali (anag.)" .)