Old and weak (6)
I believe the answer is:
senile
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">old and weak</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 senile that I've seen before include "Old and doddery" , "Suffering from ailments of old age" , "past it" , "In one's dotage" , "Affected by old age" .)