Ceremony associated with a severe hairstyle (9)
I believe the answer is:
pompadour
'hairstyle' is the definition.
(I know that pompadour is a hairstyle)
'ceremony associated with a severe' is the wordplay.
'ceremony' becomes 'pomp' (I've seen this in another clue).
'associated with' says to put letters next to each other.
'severe' becomes 'dour' (I've seen this in other clues).
'pomp'+'a'+'dour'='POMPADOUR'
(Other definitions for pompadour that I've seen before include "18th century hairstyle employing a pad at the front to add bulk" , "18th century women's hairstyle" , "Extravagant quiff" , "High Barnet" , "twenty down [HAIRDO]" .)