A clavier composition unpopular with the Roundheads (8)

I believe the answer is:

cavalier

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'unpopular with the roundheads' is the definition.
I can't tell whether this definition defines the answer.

'a clavier composition' is the wordplay.
'composition' indicates an anagram (letters arranged or composed in a different order).
'a'+'clavier'='aclavier'
'aclavier' with letters rearranged gives 'CAVALIER'.

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(Other definitions for cavalier that I've seen before include "Arbitrary, off-hand" , "... King Charles, canine breed" , "Incautious" , "supporter of the monarchy" , "Monarchist" .)

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