Tart up (8)
I believe the answer is:
prettify
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tart up</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for prettify that I've seen before include "Doll up" , "Make superficially attractive" , "tart up" , "Ornament" .)