Postal item repacked with some replacements (6)

I believe the answer is:

parcel

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'postal item' is the definition.
'parcel' can be an answer for 'item' (thesaurus). I'm unsure of the 'postal' bit.

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for parcel that I've seen before include "One wrapped" , "Packet" , "Area of land" , "Small piece of land" , "Package; piece of land" .)

I've seen this clue in the Evening Standard.

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