Row reduced by half car manufacturer's finances (9)

I believe the answer is:

bankrolls

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'finances' is the definition.

'row reduced by half car manufacturer's' is the wordplay.
'row' becomes 'bank' (I've seen this before).
'reduced by half car manufacturer' becomes 'rolls' (I can't justify this - if you can you should believe this answer much more).
'bank'+'rolls'='BANKROLLS'

Can you help me to learn more?

(Another definition for bankrolls that I've seen is " Finances, a business say".)

I've seen this clue in The Telegraph.

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