Travelling is rare in a mountain range (6)
I believe the answer is:
sierra
'a mountain range' is the definition.
(sierra is a kind of mountain range)
'travelling is rare' is the wordplay.
'travelling' indicates an anagram.
'is'+'rare'='israre'
'israre' anagrammed gives 'SIERRA'.
'in' is the link.
(Other definitions for sierra that I've seen before include "Mountain chain, S (radio comms.)" , "------ Nevada, mountains of Spain and California" , "Mountain range in Spanish-speaking countries" , "Spanish range of mountains" , "that Romeo is not after" .)