What remains of Svengali's strange spell (8)

I believe the answer is:

leavings

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'what remains' is the definition.
I can't judge whether this definition defines the answer.

'svengali's strange spell' is the wordplay.
'svengali' can be anagrammed to 'LEAVINGS'.
Though, I'm not clear how this is indicated.

'of' acts as a link.

Can you help me to learn more?

(Other definitions for leavings that I've seen before include "Svengali (anag.)" , "Refuse" , "exits" , "Worthless remnants" , "Crumbs!" .)

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

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