Italian sausage made using mostly old meat and lard (10)

I believe the answer is:

mortadella

I'm a little stuck... Click here to teach me more about this clue!

'italian sausage' is the definition.
'mortadella' can be an answer for 'sausage' (I've seen this before). I'm not sure about the 'italian' bit.

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Another definition for mortadella that I've seen is " Sausage".)

I've seen this clue in The Independent.

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