Tropical shrub (6)
I believe the answer is:
acacia
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tropical shrub</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 acacia that I've seen before include "Plant like wattle" , "Spiny tree of warm climates" , "Thorny flowering shrub" , "Thorny shrub with yellow or white-flowers" , "Shrub of warm climates" .)