The most common and most likely answer to this crossword clue is the 5 letter word SOUSA
I've seen this crossword clue in The Daily Telegraph
S
O
U
S
A
More clues leading to the result SOUSA
- Typically American composer
- Very much America's March man?
- Composer typical of America
- Donuts regularly consumed by South American composer
- Composer from America, therefore supported by America
- March man and son round America
- Thus his country marches to his tunes
- His Stars and Stripes is typically American
- Very American, ace composer
- Thus America presents one of its composers
Buddy explains!

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