Useless grant producing rant if so? (2,4)

I believe the answer is:

no good

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'useless' is the definition.
(I've seen this in another clue)

I don't understand how the remainder of the clue works.

(Other definitions for no good that I've seen before include "worthless sort" , "Useless, not worth bothering about" , "Futile; worthless" , "(Of a person) beneath contempt" , "Hopeless" .)

I've seen this clue in The Independent.

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