Pass large recess in ruin (8)
I believe the answer is:
collapse
'ruin' is the definition.
(I've seen this before)
'pass large recess' is the wordplay.
'pass' becomes 'col' (col is a kind of pass).
'large' becomes 'l'.
'recess' becomes 'apse' (apse is a kind of recess).
'col'+'l'+'apse'='COLLAPSE'
'in' is the link.
(Other definitions for collapse that I've seen before include "Give way, fail suddenly" , "Disintegration" , "Fall down or cave in" , "Faint and fall" , "Slump" .)