The most common and most likely answer to this crossword clue is the 10 letter word ALTOGETHER
I've seen this crossword clue in Independent
A
L
T
O
G
E
T
H
E
R
More clues leading to the result ALTOGETHER
- Quite some voice, good heavens!
- Regularly fail to understand that woman completely
- Wholly good air introduced by singer
- Totally special to get Hermes trousers
- Great hotel rebuilt entirely
- Article in German on singer in chorus
- Participating in deal to get Hereford United
- Leather got ruined completely
- Completely nude?
- Great hotel renovated completely
Buddy explains!

The straight part
We know that "in chorus" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in chorus = altogether.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 ALTOGETHER mean?
ALTOGETHER adverb- Without exception; wholly; completely.
- On the whole; with everything considered.