Sign that a professional person is ready to do business (5,5)

I believe the answer is:

brass plate

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'sign that a professional person' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'ready to do business' is the wordplay.
'ready' becomes 'brass' (I've seen this before).
'to do business' becomes 'plate' (I can't justify this - if you can you should give a lot more credence to this answer).
'brass'+'plate'='BRASS PLATE'

'is' is the link.

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

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