Dazzling success (5)
I believe the answer is:
eclat
'dazzling success' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for eclat that I've seen before include "Ostentation" , "Social distinction in France" , "Brilliant display -- conspicuous success" , "Brilliant success - striking effect" , "Splendour; renown" .)