Blood on prison's silverware (6,3)

I believe the answer is:

claret jug

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'silverware' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'blood on prison's' is the wordplay.
'blood' becomes 'claret' (claret can informally mean blood).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'prison' becomes 'jug' (slang term for prison).
'claret'+'jug'='CLARET JUG'

Can you help me to learn more?

(Another definition for claret jug that I've seen is " vessel for Bordeaux".)

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