Report sets down formalities (5)
I believe the answer is:
rites
'formalities' is the definition.
(I've seen this in another clue)
'report sets down' is the wordplay.
'report' shows a homophone (sound like).
'sets down' becomes 'writes' (sets down on paper).
'writes' sounds like 'RITES'.
(Other definitions for rites that I've seen before include "Ceremonial observances" , "Ceremonial forms" , "Customary observances, religious say" , "Formal ceremonial procedures" , "Social customs" .)