High-fashion dealer (7)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">high-fashion dealer</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for modiste that I've seen before include "couturier" , "old dressmaker" , "Fasionable dressmaker" , "Posh milliner or dressmaker" .)