Wrongly breaking rule — yes or no? (11)
I believe the answer is:
erroneously
'wrongly' is the definition.
(I've seen this before)
'breaking rule yes or no?' is the wordplay.
'breaking' is an anagram indicator.
'rule'+'yes'+'or'+'no'='ruleyesorno'
'ruleyesorno' is an anagram of 'ERRONEOUSLY'.
(Other definitions for erroneously that I've seen before include "In an incorrect manner" , "Wrongly" , "in a wrongful manner" , "Mistakenly" .)