Rowan (8,3)
I believe the answer is:
mountain ash
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rowan</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 mountain ash that I've seen before include "Rowan tree" , "thrives in rarefied atmosphere?" .)