Big do for a doctor (4)
I believe the answer is:
afro
'big do' is the definition.
(I've seen this in another clue)
'for a doctor' is the wordplay.
'doctor' is an anagram indicator.
'for'+'a'='fora'
'fora' anagrammed gives 'AFRO'.
(Other definitions for afro that I've seen before include "configuration of locks" , "Hairstyle with little thick curls" , "Curly hairstyle" , "little Malian, for example" , "Bushy hairstyle" .)