Supremo delayed internal change (7)
I believe the answer is:
remodel
'change' is the definition.
(remodelling is a kind of changing)
'supremo delayed internal' is the wordplay.
'internal' indicates a hidden word.
'REMODEL' is hidden within 'supremo delayed'.
(Other definitions for remodel that I've seen before include "style again" , "Reconstruct, recast" , "Alter" , "Reshape" , "Change the shape" .)