Climber's rock (4)
I believe the answer is:
crag
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">climber's rock</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(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" .)