Ceremony correct, by the sound of it (4)
I believe the answer is:
rite
'ceremony' is the definition.
(rite is a kind of ceremony)
'correct by the sound of it' is the wordplay.
'correct' becomes 'right' ('right' can be a synonym of 'correct').
'by the sound of it' indicates a 'sounds like' (homophone) clue.
'right' sounds like 'RITE'.
(Other definitions for rite that I've seen before include "Ceremony, liturgy" , "Ceremony - ritual" , "Custom" , "(Words used in) ceremonial" , "Formal procedure" .)