Follow master code of belief (5)
I believe the answer is:
dogma
'code of belief' is the definition.
(I've seen this before)
'follow master' is the wordplay.
'follow' becomes 'dog' (I've seen this before).
'master' becomes 'ma'.
'dog'+'ma'='DOGMA'
(Other definitions for dogma that I've seen before include "Set of principles laid down as incontrovertibly true" , "Inflexible principle" , "Doctrine put forward as true, not to be questioned" , "Religious doctrine proclaimed as true without proof" , "Go mad (anag.)" .)