Stopped around apex (3)
I believe the answer is:
top
'apex' is the definition.
(I've seen this in another clue)
'stopped around' is the wordplay.
'around' indicates the answer is hidden within the clue.
'TOP' is hidden in the letters of 'stopped'.
(Other definitions for top that I've seen before include "Upper side" , "Zenith" , "Summit or spinning toy" , "Better" , "SECOND PART OF 10 ACROSS" .)