The most common and most likely answer to this crossword clue is the 7 letter word CHORALE
I've seen this crossword clue in The Daily Telegraph
C
H
O
R
A
L
E
More clues leading to the result CHORALE
- Everyday duty imbued with a large and stately air
- Vocal required in revolutionary hymn
- Test said to lie within revolutionary piece of church music
- Vocal in revolutionary hymn
- Hymn tune hourly in church
- 11 Christ has alternative to drink in hymn tune
- Psalm uttered in church service finally
- Work of harmonisation is painful task after Article 50’s introduced
- Men having beer after church — where this is sung?
- Contralto’s sound accommodating alternative musical form
Buddy explains!

The straight part
We know that "this is sung" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case this is sung = chorale.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.
What does CHORALE mean?
CHORALE noun- A form of Lutheran or Protestant hymn tune.
- A chorus or choir.