Religious song but not second pious ceremonial (6)
I believe the answer is:
ritual
'ceremonial' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for ritual that I've seen before include "Ceremony or protocol" , "Customary (eg religious) practice" , "Codified ceremony" , "Actions performed as in a religious ceremony" , "Customary observance or practice" .)