ain't going to cut it = will not be good enough / will not be sufficient.
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Mister Micawber.Oh, oh !! Mister Micawber, thanks for your help.
ain't going to cut it = will not be good enough / will not be sufficient.
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Mister Micawber.
Maybe. It does not mean 'unable to deal with', though. In your excerpt, 'soon enough' is not a sufficient answer (= it [your answer] ain't going to cut it).
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