Undo, unlace (5)
I believe the answer is:
untie
I believe this is a double definition.
'undo' is the first definition.
(I know that undo can be written as untie)
'unlace' is the second definition.
(I know that unlace can be written as untie)
(Other definitions for untie that I've seen before include "Set free" , "Separate" , "Release, loosen" , "Free from binds" , "Open a knot" .)