Pageant prize (5)
I believe the answer is:
tiara
'pageant prize' 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, ornamental headgear" , "expensive headwear" , "Woman's headdress for very formal occasions" , "Half a crown!" , "Jewelled coronet" .)