Not many occupy a safe world (3)
I believe the answer is:
few
'not many' is the definition.
('few' is the opposite to 'many')
'occupy a safe world' is the wordplay.
'occupy' indicates a hidden word (I've seen 'occupying' mean this (letters for the answer occupy part of the clue)).
'FEW' is hidden in the letters of 'safe world'.
(Other definitions for few that I've seen before include "Considerable number, ironically" , "'''Many are called but ... are chosen'' (Bible) (3)'" , "Not many, just a handful" , "Hardly anyone" , "Relatively small number" .)