The most common and most likely answer to this crossword clue is the 8 letter word SCHUBERT
I've seen this crossword clue in The Times
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More clues leading to the result SCHUBERT
- Classical composer — namely Parry, perhaps?
- For songwriter, insert fish?
- Composer‘s arrangement for butchers
- Bruch set out to be a composer
- Composer curbs the arrangement
- Composer from Switzerland, exceptional type, good person to have around
- Trout supplier disoriented in butchers?
- Old musician butchers new composition
- A noted work of his remained unfinished
- Crackpot butchers composer
Buddy explains!

The straight part
We know that "Classical composer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case classical composer = schubert.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.