Arranged grandiose changes (9)
I believe the answer is:
organised
'arranged' is the definition.
(organising is a kind of arranging)
'grandiose changes' is the wordplay.
'changes' indicates anagramming the letters.
'grandiose' with letters rearranged gives 'ORGANISED'.
(Other definitions for organised that I've seen before include "Set up, mobilised" , "Arranged - structured" , "Set up,mobilised" , "Methodical" , "fixed up" .)