Song book, one helping in church (3,6)
I believe the answer is:
lay reader
'one helping in church' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'song book' is the wordplay.
'song' becomes 'lay' (poetic term for a song).
'book' becomes 'reader' (reader is a kind of book).
'lay'+'reader'='LAY READER'
Can you help me to learn more?
(Other definitions for lay reader that I've seen before include "who carries out some services" , "Parish assistant" , "volunteer for service?" , "assistant to minister" , "Minister's assistant" .)