Crossword Genius

Castigation about a demonstration (7)

Ross

I believe the answer is:

reproof

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

'about a demonstration' is the wordplay.
'about' becomes 're' ('re' means regarding or about).
'a demonstration' becomes 'proof' (I've seen this before).
're'+'proof'='REPROOF'

(Other definitions for reproof that I've seen before include "Reprimand" , "Dressing down" , "what mac no longer keeping one dry needs?" , "Rebuke" , "Ticking off" .)

I've seen this clue in the Evening Standard.
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