Wander in the mountains (5)
I believe the answer is:
range
I believe this is a double definition.
'wander' is the first definition.
('range' can be a synonym of 'wander')
'mountains' is the second definition.
(I've seen this before)
'in the' acts as a link.
(Other definitions for range that I've seen before include "Series of hills or mountains" , "Open land for livestock in the US" , "spectrum" , "Array" , "1 across [CLASSIFY]" .)