No longer interested in (4)
I believe the answer is:
over
'no longer interested in' is the definition.
(I've seen this in another clue)
This is the entire clue.
(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" .)