Steep rock faces (6)
I believe the answer is:
cliffs
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">steep rock faces</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for cliffs that I've seen before include "Crags, Precipies" , "Sheer rock faces overlooking sea" , "High steep rocks" , "Steep rock faces" , "Precipices" .)