Dash about in capital ceaselessly
I believe the answer is:
eclat
'dash' is the definition.
(I've seen this in another clue)
'about in capital ceaselessly' is the wordplay.
'about' says the letters should be written backwards.
'in' indicates a hidden word.
'talce' is hidden in the letters of 'capital ceaselessly'.
'talce' reversed gives 'ECLAT'.
(Other definitions for eclat that I've seen before include "Loud applause" , "Brilliance" , "Fame -- style" , "Splendour; renown" , "Splash" .)