A hint to overturn? (3)
I believe the answer is:
tip
I believe this is a double definition.
'a hint' is the first definition.
(I know that hint can be written as tip)
'overturn?' is the second definition.
(I've seen this in another clue)
'to' is the link.
(Other definitions for tip that I've seen before include "Useful suggestion" , "single piece of asparagus, perhaps" , "Topple; advice" , "End - pourboire" , "Give the likely winner for gratuity" .)