Settles on the rim — effect of ground movement (8)
I believe the answer is:
landslip
'settles on the rim effect' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'ground movement' is the wordplay.
'ground' becomes 'land' (synonyms).
'movement' becomes 'slip' (slip is a kind of movement).
'land'+'slip'='LANDSLIP'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for landslip that I've seen before include "Avalanche" , "Fall of earth, stones, etc down slope" , "Rockfall" , "Earth movement" .)