Big hair (4)
I believe the answer is:
afro
'big hair' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for afro that I've seen before include "Big hairstyle" , "Hair in tight curls" , "Big hair?" , "Hair-style from Dark Continent" , "Luxuriant (black) hairstyle" .)