Over the hill (4,2)
I believe the answer is:
past it
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">over the hill</span>' is the definition.<br/ ><span class="explanation-format__explanation">(both can mean getting old)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for past it that I've seen before include "No longer capable" , "not helped by age" , "No longer in one's prime" , "Informally too old to function" , "No longer able, too old or decrepit" .)