Grounds for belief (8)
I believe the answer is:
evidence
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">grounds for belief</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 evidence that I've seen before include "Signs, indications" , "The basis for belief or disbelief" , "authentication" , "Testimony - verification" , "Facts given in court" .)