A boast (5)
I believe the answer is:
vaunt
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a boast</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that boast can be written as vaunt)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for vaunt that I've seen before include "Show off" , "Talk boastfully of" , "Boast about (something), often excessively" , "crow" , "brag" .)