Arrives at rim to see rockfall? (8)
I believe the answer is:
landslip
'rockfall?' is the definition.
(I've seen this before)
'arrives at rim' is the wordplay.
'arrives' becomes 'lands' (landing is a kind of arriving).
'at' is a charade indicator (letters next to each other).
'rim' becomes 'lip' (both can mean the edge of something).
'lands'+'lip'='LANDSLIP'
'to see' is the link.
(Other definitions for landslip that I've seen before include "Earth movement" , "Rockfall" , "Fall of earth, stones, etc down slope" , "Avalanche" .)