More than mere business acquaintances (4,7)

I believe the answer is:

firm friends

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'more than mere' is the definition.
I can't tell whether this definition defines the answer.

'business acquaintances' is the wordplay.
'business' becomes 'firm' (firm is a kind of business).
'acquaintances' becomes 'friends' ('friend' can be a synonym of 'acquaintance').
'firm'+'friends'='FIRM FRIENDS'

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I've seen this clue in The Globe and Mail.

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