*Bejeweled topper (5)
'bejeweled 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 "it goes to one's head!" , "Pope's triple crown" , "Jewelled headwear" , "Jewelled head band" , "Type of diadem" .)
(Other definitions for crown that I've seen before include "Monarch's headgear" , "Coin; royal headgear" , "Old coin; whack on head" , "repair for damaged tooth" , "The sovereign" .)