Ceremonial procedure which is utterly correct (4)
I believe the answer is:
rite
'ceremonial procedure' is the definition.
(I've seen this before)
'utterly correct' is the wordplay.
'utterly' shows a homophone (sound like) (as uttered).
'correct' becomes 'right' (right can mean correct).
'right' is a homophone of 'RITE'.
'which is' is the link.
(Other definitions for rite that I've seen before include "Ceremony, liturgy" , "Custom" , "Formal procedure" , "Solemn ceremony" , "Uncomplaining person" .)