Cliffside debris (5)
I believe the answer is:
scree
'cliffside debris' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for scree that I've seen before include "bits of rock" , "Debris at the foot of a cliff" , "Safeguard" , "Small loose stones on a mountainside" , "Mass of loose rocks at the base of a cliff" .)