Mad hysteria about large mullet, say (9)
I believe the answer is:
hairstyle
'mullet say' is the definition.
(I know that mullet is a hairstyle)
'mad hysteria about large' is the wordplay.
'mad' indicates anagramming the letters.
'about' indicates putting letters inside.
'large' becomes 'L' (eg in clothes sizes).
'hysteria' is an anagram of 'hairstye'.
'hairstye' placed around 'l' is 'HAIRSTYLE'.
(Other definitions for hairstyle that I've seen before include "Pageboy or bob, say" , "Design of crowning glory" , "DA possibly" .)