Free tips from parents' siblings ignored (5)
I believe the answer is:
'free' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for untie that I've seen before include "Loose bonds" , "Undo, unlace" , "Loosen, as laces" , "Remove fastenings from" , "Unite (anag)" .)