Uncertainty (5)
I believe the answer is:
doubt
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">uncertainty</span>' is the definition.<br/ ><span class="explanation-format__explanation">(doubt is a kind of uncertainty)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for doubt that I've seen before include "Misgiving" , "Suspect" , "Uncertainty, unsureness" , "One certainly can't have it" , "Don't be so sure!" .)