Simply depend on turning up (6)
I believe the answer is:
purely
'simply' is the definition.
(thesaurus)
'depend on turning up' is the wordplay.
'depend' becomes 'rely' (I've seen this before).
'on' is a charade indicator (letters next to each other).
'turning' shows that the letters should be reversed in order.
'up' backwards is 'pu'.
'rely' after 'pu' is 'PURELY'.
(Other definitions for purely that I've seen before include "Entirely, exclusively" , "Entirely; chastely" , "Simply and solely" , "Wholly, unconditionally" , "Strictly, solely" .)