Fall down in mountain pass and expire (8)
I believe the answer is:
collapse
'fall down' is the definition.
(I've seen this before)
'mountain pass and expire' is the wordplay.
'mountain pass' becomes 'col' (col is a kind of mountain pass).
'and' is a charade indicator (letters next to each other).
'expire' becomes 'lapse' (I've seen this before).
'col'+'lapse'='COLLAPSE'
'in' is the link.
(Other definitions for collapse that I've seen before include "Abrupt failure of function" , "fold" , "downfall" , "Founder" , "Suddenly fall down or give way" .)