Moral and oath C-in-C provided for a type of religion (5,8)
I believe the answer is:
roman catholic
'a type of religion' is the definition.
'moral and oath c-in-c provided' is the wordplay.
'and' means one lot of letters go next to another (I've seen this in other clues).
'provided' indicates an anagram (I've seen 'provide' mean this).
'oath'+'c'+'in'+'c'='oathcinc'
'moral' after 'oathcinc' is 'oathcincmoral'.
'oathcincmoral' anagrammed gives 'ROMAN CATHOLIC'.
'for' acts as a link.
(Other definitions for roman catholic that I've seen before include "RC in full" , "Its head is the Pope" , "Church member" , "Religious believer" .)