New opposition (3)

I believe the answer is:

old

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'new opposition' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.

This is all the clue.

Can you help me to learn more?

(Other definitions for old that I've seen before include "Elderly" , "Venerable" , "Long in the tooth" , "Stale" , "Obsolete" .)

I've seen this clue in the Evening Standard.

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