How to give up Christmas leftovers? (4,6)

I believe the answer is:

cold turkey

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'christmas leftovers?' is the definition.
The definition suggests a singular noun which matches the answer.

I can't explain the rest of the clue.

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(Other definitions for cold turkey that I've seen before include "Problems of withdrawal" , "When horse perhaps barred" , "Quick way to come off horse" , "Depression" , "Cure" .)

I've seen this clue in the Sydney Morning Herald.

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