After capture, saw denial (10)

I believe the answer is:

gainsaying

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

'after capture saw' is the wordplay.
'after capture' becomes 'gain' (I can't explain this - if you can you should give a lot more credence to this answer).
'saw' becomes 'saying' (a saw can mean a proverb or maxim).
'gain'+'saying'='GAINSAYING'

Can you help me to learn more?

(Other definitions for gainsaying that I've seen before include "denial" , "Not agreeing" .)

I've seen this clue in The Times and The Sunday Times.

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