Swamp tree (8)
I believe the answer is:
mangrove
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">swamp 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 mangrove that I've seen before include "Swamp tree" , "that grows in swamps" , "Tree growing on tropical coasts and in muddy swamps" , "one that's swamped?" , "Tree of coastal swamps" .)