Pull strings? (6)
(Other definitions for unlace that I've seen before include "Loosen" , "Untie" .)
'pull strings?' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for undo that I've seen before include "Ruin or loose" , "Cancel, annul; open" , "Disentangle" , "Release button, knot etc" , "Open button or ruin" .)