Of high mountains (6)
I believe the answer is:
alpine
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">of high mountains</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 alpine that I've seen before include "Nepali (anag.)" , "Plant of high mountains" , "Relating to a European mountain range" , "from Germany, Austria etc" , "Native growing up in mountainous area" .)