Senility (6)
I believe the answer is:
dotage
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">senility</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that senility can be written as dotage)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for dotage that I've seen before include "decrepitude" , "when one's powers decline" , "Mental infirmity in old age" , "Foolish later life" , "Senile years" .)