Brilliant success (5)
I believe the answer is:
eclat
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">brilliant success</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 eclat that I've seen before include "Brilliant display -- conspicuous success" , "Brilliance" , "Splendour; renown" , "Enthusiastic approval" , "Showy effect (Fr.)" .)