Authoritative doctrine (5)
I believe the answer is:
dogma
'authoritative doctrine' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for dogma that I've seen before include "Code of beliefs accepted as authoritative" , "Opinion viewed as truth?" , "Incontrovertible set of principles" , "Set of beliefs" , "Go mad (anag.)" .)