Familiar airs unsettled saturnine guest (9,5)

I believe the answer is:

signature tunes

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'familiar airs' is the definition.
'signature tunes' can be an answer for 'airs' (signature tune is a kind of air). I am not sure about the 'familiar' bit.

'unsettled saturnine guest' is the wordplay.
'unsettled' is an anagram indicator.
'saturnine'+'guest'='saturnineguest'
'saturnineguest' is an anagram of 'SIGNATURE TUNES'.

Can you help me to learn more?

(Another definition for signature tunes that I've seen is " theme songs - with 22d".)

I've seen this clue in The Telegraph.

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