Yellow-flowered tree (8)
I believe the answer is:
laburnum
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">yellow-flowered tree</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 laburnum that I've seen before include "Source of poison" , "Shrub known as golden chain" , "Poisonous shrub with yellow flowers" , "Tree with yellow flowers and poisonous seeds" , "Poisonous plant" .)