Overconfidence (5)
I believe the answer is:
front
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">overconfidence</span>' is the definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for front that I've seen before include "Head" , "Meteorological boundary between different air masses" , "Impudence" , "confident manner?" , "Boldness of manner" .)