Sparkling topper (5)
I believe the answer is:
tiara
'sparkling topper' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tiara that I've seen before include "Type of diadem" , "Crescent-shaped headdrsss or Pope's diadem" , "Pope's triple-tiered crown" , "Woman's crescent-shaped ornamental headdress" , "It might go to one's head" .)