System of religious belief (5)
I believe the answer is:
creed
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">system of religious belief</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for creed that I've seen before include "Catechism" , "System of religious principles" , "restricted set of principles" , "System of principles or beliefs" , "Church doctrine" .)