Harmful, detrimental (7)
I believe the answer is:
adverse
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">harmful</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">detrimental</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for adverse that I've seen before include "Unfavourable to evaders" , "'Contrary, untoward (7)'" , "Opposed to or unfavourable" , "Evaders being harmful" , "negative result" .)