Tribal roar, occasionally displaying headdress (5)
I believe the answer is:
tiara
'headdress' is the definition.
(tiara is a kind of headdress)
'tribal roar occasionally' is the wordplay.
'occasionally' means one should take alternating letters (letters taken at regular intervals or occasions).
'tribal'+'roar'='tribalroar'
The alternating letters of 'tribalroar' are 'TIARA'.
'displaying' acts as a link.
(Other definitions for tiara that I've seen before include "Jewelled head band" , "Woman's crescent-shaped ornamental headdress" , "Item of jewellery" , "Top decoration" , "Great delight" .)