Wonder Woman's headpiece (5)
I believe the answer is:
tiara
'wonder woman's headpiece' 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 "Woman's headdress for very formal occasions" , "Jewelled headband" , "Pope's triple-tiered crown" , "Jewelled head-ornament" , "Women's head ornament" .)