Behave ostentatiously (4,3)
I believe the answer is:
show off
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">behave ostentatiously</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 show off that I've seen before include "Flaunt - exhibitionist" , "In conceitedness" , "Behave ostentatiously" , "Display ostentatiously, try to impress" , "Ostentatious person" .)