Bad rule broken that's likely to last (7)
I believe the answer is:
durable
'likely to last' is the definition.
(I've seen this before)
'bad rule broken' is the wordplay.
'broken' indicates anagramming the letters.
'bad'+'rule'='badrule'
'badrule' is an anagram of 'DURABLE'.
'that's' acts as a link.
(Other definitions for durable that I've seen before include "Firm" , "Tough and long-wearing" , "Made to last" , "Lasting a long time" , "Long-lasting and hard-wearing" .)