Story about bringing in constant brilliance
I believe the answer is:
eclat
'brilliance' is the definition.
(eclat means brilliance or flair)
'story about bringing in constant' is the wordplay.
'story' becomes 'tale' (synonyms).
'about' says the letters should be written backwards.
'bringing in' means one lot of letters goes inside another.
'constant' becomes 'c' (mathematical abbreviation).
'tale' reversed gives 'elat'.
'elat' going around 'c' is 'ECLAT'.
(Other definitions for eclat that I've seen before include "great success" , "Splendour; renown" , "French renown" , "Brilliant display -- conspicuous success" , "Enthusiastic approval" .)