… classical star back in tune (4)
I believe the answer is:
sole
'classical star back in tune' is the definition.
The definition and answer can be both related to change as well as being verbs in their base form.
Perhaps there's an association between them I don't understand?
'star back in tune' is the wordplay.
'star' becomes 'sol' (I've seen this before).
'back in' indicates one should take the final letters (the 'back' of the word).
The last letter of 'tune' is 'e'.
'sol'+'e'='SOLE'
Can you help me to learn more?
(Other definitions for sole that I've seen before include "Lone; part of foot" , "Underside of footwear" , "Exclusive class of fish" , "A lone sort of fish - lose it" , "Fish - alone" .)