What chopping karate instructor's rear does is clear (5,5)

I believe the answer is:

makes sense

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'what chopping karate instructor's rear' is the definition.
I can't judge whether this definition defines the answer.

'does is clear' is the wordplay.
'does' becomes 'makes' ('make' can be a synonym of 'do').
'is clear' becomes 'sense' (I can't explain this - if you can you should believe this answer much more).
'makes'+'sense'='MAKES SENSE'

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I've seen this clue in The Independent.

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