Sanitary principles (7)
I believe the answer is:
hygiene
'sanitary principles' is the definition.
This is all the clue.
(Other definitions for hygiene that I've seen before include "Condition promoting sanitary practices" , "Principles and practice of cleanliness" , "Sanitary practices conducive to health" , "Cleanliness, sanitation" , "The practice of cleanliness for health reasons" .)