Brave leader (8)
I believe the answer is:
'brave leader' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for geronimo that I've seen before include "shout during dive" , "Whee!; Apache chief" , "Famous Apache chieftain" , "helicopter paratroops' departure call?" , "cry from bungee jumper?" .)