Rubbish! He'd gone through training and was very keen (3-3)

I believe the answer is:

red-hot

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'very keen' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for red-hot that I've seen before include "(Of information) very recently received" , "Of news, new and burning" , "Flower (just out of the fire?)" , "Extremely passionate" , "Very exciting - glowing" .)

I've seen this clue in the Evening Standard.

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