Extra large cat receives shocking treatment in scrap for seat (2-8)

I believe the answer is:

by-election

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'scrap for seat' is the definition.
The definition suggests a singular noun which matches the answer.

'extra large cat receives shocking treatment' is the wordplay.
'extra' becomes 'bye' (bye is a type of extra in cricket).
'large cat' becomes 'lion' (I've seen this before).
'receives' means one lot of letters goes inside another (inserted letters are received).
'shocking treatment' becomes 'ect' (electro-convulsive therapy).
'lion' going around 'ect' is 'lection'.
'bye'+'lection'='BY-ELECTION'

'in' is the link.

Can you help me to learn more?

I've seen this clue in The Independent.

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