Any horn I'm playing is tuneful (2,7)

I believe the answer is:

in harmony

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'tuneful' is the definition.
Both the answer and definition are adjectives. Perhaps they are linked in a way I don't understand?

'any horn i'm playing' is the wordplay.
'playing' is an anagram indicator.
'any'+'horn'+'im'='anyhornim'
'anyhornim' is an anagram of 'IN HARMONY'.

'is' acts as a link.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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