Font flourish (5)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">font flourish</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for serif that I've seen before include "Typeface decoration" , "Small line used in printing type" , "stroke of the pen" , "Feature of some typefaces" , "Style of type-face" .)