I’d put in note reflecting change (4)
I believe the answer is:
edit
'change' is the definition.
(edit can mean to change or alter)
'i'd put in note reflecting' is the wordplay.
'put in' is an insertion indicator.
'note' becomes 'te' (musical note).
'reflecting' shows that the letters should be reversed in order.
'id' put inside 'te' is 'tide'.
'tide' backwards is 'EDIT'.
(Other definitions for edit that I've seen before include "doctor" , "Prep for press" , "Redact, perhaps" , "Ready for publication" , "Amend a publication" .)