Composes ceremonies by ear (6)
I believe the answer is:
writes
'composes' is the definition.
('write' can be a synonym of 'compose')
'ceremonies by ear' is the wordplay.
'ceremonies' becomes 'rites' (rite is a kind of ceremony).
'by' is a charade indicator (letters next to each other).
'ear' becomes 'w' (I can't justify this - if you can you should believe this answer much more).
'rites' after 'w' is 'WRITES'.
Can you help me to learn more?
(Other definitions for writes that I've seen before include "Puts words on paper" , "Creates (a book)" , "Communicates by letter" , "Pens" , "Drops a line" .)