Posted, perhaps, with a colourful card? (4,3)

I believe the answer is:

sent off

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'posted perhaps with a colourful card?' is the definition.
I can't tell whether this definition defines the answer.

'posted perhaps with' is the wordplay.
'posted' becomes 'sent' ('send' can be a synonym of 'post').
'perhaps with' becomes 'off' (I can't explain this - if you can you should give a lot more credence to this answer).
'sent'+'off'='SENT OFF'

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I've seen this clue in the Evening Standard.

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