Siberian forest (5)
I believe the answer is:
taiga
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">siberian forest</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 taiga that I've seen before include "Marshy pine forest" , "Arctic coniferous region" , "Siberian subarctic forest(s)" , "Northern region" , "northern forest" .)