Sparkly topper (5)
I believe the answer is:
tiara
'sparkly topper' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tiara that I've seen before include "Jewelled headband" , "Jewelled head-ornament" , "Jewelled coronet" , "Jewelled headpiece" , "Half a crown!" .)