A course curtailed and altered for a singer (6)

I believe the answer is:

caruso

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'for a singer' is the definition.
(opera singer Enrico Caruso)

I can't explain the rest of the clue.

(Other definitions for caruso that I've seen before include "Classical tenor" , "Enrico ......, late great Italian tenor" , "Enrico ...... was famous Italian tenor" , "Enrico ---, early C20 tenor" , "Enrico ---, operatic tenor" .)

I've seen this clue in The Globe and Mail.

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