Festive polka he'd danced, an unexpected turn-up (5,2,3,5)

I believe the answer is:

speak of the devil

'an unexpected turn-up' is the definition.
(phrase spoken when someone arrives suddenly)

'festive polka he'd danced' is the wordplay.
'danced' indicates anagramming the letters (I've seen 'dance' mean this).
'festive'+'polka'+'hed'='festivepolkahed'
'festivepolkahed' anagrammed gives 'SPEAK OF THE DEVIL'.

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app