A note shiftily to make up (5)
I believe the answer is:
atone
'make up' is the definition.
(I've seen this before)
'a note shiftily' is the wordplay.
'shiftily' indicates anagramming the letters (I've seen this in other clues).
'note' is an anagram of 'tone'.
'a'+'tone'='ATONE'
'to' is the link.
(Other definitions for atone that I've seen before include "Make amends, being at one" , "In agreement - sounds singular" , "remedy" , "Make redress" , "Make amends (for something)" .)