Mystery writer Marsh (5)
I believe the answer is:
ngaio
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">mystery writer marsh</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ngaio that I've seen before include "foreign tree" , "- Marsh, NZ author" , "- Marsh, NZ detective novelist" , "- - Marsh, crime writer" , "wood" .)