Himalayan mountain (7)
I believe the answer is:
everest
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">himalayan mountain</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 everest that I've seen before include "Huge achievement - highest climb" , "Himalayan peak" , "One conquered in 1953" , "Highest peak" , "Mountain on the Nepal-Tibet border" .)