Toxic (9)
I believe the answer is:
poisonous
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">toxic</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for poisonous that I've seen before include "Potentially deadly" , "Extremely malicious" , "Noxious; malicious" , "Toxic, venomous" , "not safe to drink" .)