Leaf-rot displays hair style (4)
I believe the answer is:
afro
'hair style' is the definition.
(I've seen this in another clue)
'leaf-rot displays' is the wordplay.
'displays' indicates the answer is hidden within the clue (part of the clue displays the answer).
'AFRO' can be found hidden inside 'leaf rot'.
(Other definitions for afro that I've seen before include "Tightly-curled 4 down" , "Of hair style, tightly curled and bushy" , "shock treatment?" , "Hair-style from Dark Continent" , "Hairstyle with little thick curls" .)