Decoys that break the rules (5)
I believe the answer is:
lures
'decoys' is the definition.
(I know this)
'break the rules' is the wordplay.
'break' indicates an anagram.
'rules' anagrammed gives 'LURES'.
'that' is the link.
(Other definitions for lures that I've seen before include "Tempts or entices" , "Draws" , "Rules with decoys" , "Baits or attractions" , "Baits, decoys" .)