Set of principles or standards (4)
I believe the answer is:
code
I believe this clue is a double definition.
'set of principles' is the first definition.
(I've seen this in another clue)
'standards' is the second definition.
(I have seen 'Ethical standards' mean 'code' so perhaps 'standards' could also mean 'code')
(Other definitions for code that I've seen before include "Cipher - set of principles" , "Secret system of letters. words etc" , "Ethical standards" , "Encryption, disguised language" , "Eg, Morse" .)