Weaken, enfeeble (10)
I believe the answer is:
debilitate
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">weaken</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that debilitate is a more specific form of the action the weaken)</span><br/ ><br/ >'<span class="explanation-format__original">enfeeble</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for debilitate that I've seen before include "Weaken" , "Make very weak" .)