Affectedly genteel (2-2-2)
I believe the answer is:
la-di-da
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">affectedly genteel</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 la-di-da that I've seen before include "Stuck-up" , "Affectedly genteel" , "Pretentious, snobbish" , "Informally, having affected manner of pronunciation" , "Hoity-toity" .)