Fundamental belief (5)
I believe the answer is:
tenet
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fundamental belief</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for tenet that I've seen before include "Doctrine; principle held" , "A belief or credo - it's a palindrome" , "you may believe in it" , "Article of faith; doctrine" , "Key principle" .)