Vain boaster (8)
I believe the answer is:
braggart
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">vain boaster</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for braggart that I've seen before include "Vain boaster" , "Boastful person" , "self-publicist" , "Big boaster" , "Show-off" .)