Summit; crest (4)
I believe the answer is:
brow
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">summit</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that brow is a type of summit)</span><br/ ><br/ >'<span class="explanation-format__original">crest</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that brow is a type of crest)</span><br/ ><br/ ></span>
(Other definitions for brow that I've seen before include "Peak of a hill" , "Mopped part of the head" , "Hill part -- head part" , "Crest" , "Forehead, sometimes knitted" .)