Climber's rock (4)
I believe the answer is:
crag
'climber's rock' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for crag that I've seen before include "Steep rugged rock or cliff" , "Rough, steep rock face" , "Steep, rugged peak" , "Avant-garde" , "Steep, overhanging rock" .)