The rowan tree (8,3)
I believe the answer is:
mountain ash
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">the rowan tree</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for mountain ash that I've seen before include "thrives in rarefied atmosphere?" , "Rowan tree" .)