She parks by building way across mountains (6,4)
I believe the answer is:
khyber pass
'way across mountains' is the definition.
'she parks by building' is the wordplay.
'building' indicates an anagram.
'she'+'parks'+'by'='sheparksby'
'sheparksby' is an anagram of 'KHYBER PASS'.
(Other definitions for khyber pass that I've seen before include "Mountainous route" , "Pakistan/Afghanistan border route" , "way across the mountains" , "Asian invasion route" .)