Rotten, worthless and wrong in 1A (3,4)

I believe the answer is:

off base

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'wrong in 1a' is the definition.
I can't judge whether this defines the answer.

'rotten worthless' is the wordplay.
'rotten' becomes 'off' (rotten food is 'off').
'worthless' becomes 'base' (I've seen this before).
'off'+'base'='OFF-BASE'

'and' acts as a link.

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