Loosen laces (5)
I believe the answer is:
untie
'loosen laces' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for untie that I've seen before include "Loosen ropes or knots" , "Remove ropes, unfasten" , "Undo, unfasten" , "Loose bonds" , "Separate" .)