The most common and most likely answer to this crossword clue is the 9 plus 5 letter word GREGORIAN CHANT
G
R
E
G
O
R
I
A
N
C
H
A
N
T
More clues leading to the result GREGORIAN CHANT
- Sacred performance changing rate, or otherwise
- A Grecian throng reworked religious song
- Silly charging a tenor for old song
- Organ teaching possibly involves source of religious music in church
- Singing in the abbey, received constant upset with Scot’s crack about top note
- Changing? Rare to make this heard in church
- Either of the Chappel brothers can have hard time — prayer's the answer
- Arrangement of this music could leave creator hanging
Buddy explains!
The straight part
We know that "heard in church" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case heard in church = gregorian chant.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.