Let loose
'let loose' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for untie that I've seen before include "Undo a knot" , "Release, loosen" , "Unite (anag)" , "Remove fastenings from" , "Disconnect; release" .)
'let loose' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for unleash that I've seen before include "Flee from restraint, allow to pursue like dog" , "Free from control" , "Shun ale to free from restraint" , "Let go" , "Let free" .)