Debilitated (6)
I believe the answer is:
infirm
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">debilitated</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for infirm that I've seen before include "unstable" , "Feeble, decrepit" , "Physically weak as from old age" , "'Weak, ill (6)'" , "Sickly" .)