One who's past it (3-4)
I believe the answer is:
has-been
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">one who's past it</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for has-been that I've seen before include "Banshee (anag.)" , "One who's past it" , "Person no longer famous or successful" , "One no longer important" , "One-time leading light who's faded" .)