The attraction of a new rule (4)
I believe the answer is:
lure
'the attraction' is the definition.
(lure is a kind of attraction)
'a new rule' is the wordplay.
'a new' is an anagram indicator.
'rule' with letters rearranged gives 'LURE'.
'of' acts as a link.
(Other definitions for lure that I've seen before include "Tempt with some kind of reward" , "'Entice, tempt (4)'" , "Enticement" , "It's used to attract fish" , "Temptation" .)