Itches to change the rules of conduct (6)
I believe the answer is:
ethics
'rules of conduct' is the definition.
(I've seen this in another clue)
'itches to change' is the wordplay.
'to change' indicates anagramming the letters.
'itches' anagrammed gives 'ETHICS'.
'the' acts as a link.
(Other definitions for ethics that I've seen before include "Code of practice for professional people" , "Moral code" , "Codes of behaviour for business people" , "rules of conduct" , "Science of moral principles" .)