The most common and most likely answer to this crossword clue is the 4 letter word OPUS
I've seen this crossword clue in The Times
O
P
U
S
More clues leading to the result OPUS
- Ring up about second musical work
- Soup prepared for work
- Cook soup for work
- Love piano accompaniment for American piece of music
- Love drink? Must turn up for work
- Work available in shop usually
- Musical work starting off piano, ultimately strident
- Rising at university, inspired by outstanding work
- One’s composed — there’s nothing the matter?
- Influential company take month off work
Buddy explains!

The straight part
We know that "One’s composed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one’s composed = opus.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 OPUS mean?
OPUS noun- A work of music or set of works with a specified rank in an ordering of a composer's complete published works.
- A work, especially of art.