Belief in one god (6)
I believe the answer is:
theism
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">belief in one god</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for theism that I've seen before include "Belief in a deity" , "Belief in a creator" , "of faith" , "The doctrine or belief in the existence of a God or gods" , "Belief in existence of a God revealed to man" .)