Champion sore after training (6)

I believe the answer is:

peachy

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'champion' is the definition.
Both the answer and definition are adjectives. Maybe there's an association between them I don't understand?

'sore after training' is the wordplay.
'sore' becomes 'achy' (I've seen this before).
'after' is a charade indicator (letters next to each other).
'training' becomes 'PE' (Physical Education).
'achy' put after 'pe' is 'PEACHY'.

Can you help me to learn more?

(Other definitions for peachy that I've seen before include "Delicious" , "excellent!" .)

I've seen this clue in The Telegraph.

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