Alter or revise (6)
I believe the answer is:
change
I believe this is a double definition.
'alter' is the first definition.
(I know that alter can be written as change)
'revise' is the second definition.
(thesaurus)
(Other definitions for change that I've seen before include "Alteration" , "Conversion" , "Novelty" , "Alter the money returned" , "protean" .)