These not wanted after I saw some attacking strokes (7)

I believe the answer is:

offcuts

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'these not wanted after i saw some' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'attacking strokes' is the wordplay.
'attacking' becomes 'off' (I am not sure about this - if you are sure you should believe this answer much more).
'strokes' becomes 'cuts' (cut is a kind of stroke).
'off'+'cuts'='OFFCUTS'

Can you help me to learn more?

I've seen this clue in The Guardian.

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