Rule out bait (4)
I believe the answer is:
lure
'bait' is the definition.
(I know that bait is a kind of lure)
'rule out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'rule' anagrammed 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" .)