The radiant centre of a Schubert piece (3)
I believe the answer is:
hub
'the radiant centre' is the definition.
'hub' can be an answer for 'centre' (hub is a kind of centre). I'm not sure about the 'the radiant' bit.
'of a schubert piece' is the wordplay.
'of' indicates the answer is hidden within the clue.
'HUB' is hidden in the letters of 'schubert piece'.
Can you help me to learn more?
(Other definitions for hub that I've seen before include "Centre (of network)" , "Centre of activity" , "Wheel's centre" , "Nave of a wheel" , "Focus" .)