Study of morals (6)
I believe the answer is:
ethics
'study of morals' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ethics that I've seen before include "Codes of standards in business" , "Motivation based on ideas of right and wrong" , "Itches (anag)" , "Code of behaviour" , "Codes of behaviour for professional people" .)