Musical tenor quits old form of Islam (3,7)
I believe the answer is:
cat stevens
'old form of islam' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'musical tenor quits' is the wordplay.
'musical' becomes 'Cats' (Andrew Lloyd Webber musical).
'tenor' becomes 't'.
'quits' becomes 'evens' (as in 'call it quits').
'cats'+'t'+'evens'='CAT STEVENS'
Can you help me to learn more?
I've seen this clue in The Sunday Times and The Times.
Want a hint initially instead of a full solution?
Install my app