Rain in ruin? (8)
I believe the answer is:
downfall
This clue is a double definition.
'rain' is the first definition.
(I have seen 'heavy rain' mean 'downfall' so perhaps 'rain' could also mean 'downfall')
'ruin?' is the second definition.
(I've seen this before)
'in' acts as a link.
(Other definitions for downfall that I've seen before include "Failure (after successful career?)" , "state of ruin" , "Cloudburst" , "heavy rain" , "Collapse, ruin" .)