Rule out bait (4)
'bait' is the definition.
('lure' can be a synonym of 'bait')
'rule out' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'rule' with letters rearranged gives 'LURE'.
(Other definitions for lure that I've seen before include "Attraction", "'Entice, tempt (4)'", "draw", "Attract with bait", "Tempt with some kind of reward".)