A number break a rule with bait (6)
I believe the answer is:
allure
'bait' is the definition.
(thesaurus)
'a number break a rule' is the wordplay.
'number' becomes 'l' (L is an example**).
'break' indicates anagramming the letters.
'rule' with letters rearranged gives 'lure'.
'a'+'l'+'lure'='ALLURE'
'with' acts as a link.
(Other definitions for allure that I've seen before include "Glamorous appeal" , "Seduction" , "What siren may do" , "Enchanting attractiveness" , "Power to attract by personal charm" .)