No longer interested in (4)
I believe the answer is:
over
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">no longer interested in</span>' is the definition.<br/ ><span class="explanation-format__explanation">(as in being over an ex)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for over that I've seen before include "Given too much money" , "Finished like round of bowling in cricket" , "Invalidate - upset" , "balls > left" , "Exceeding - finished" .)