Highly-prized safe that tramp makes off with (9)

I believe the answer is:

treasured

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'prized safe that tramp makes off with' is the definition.
'treasured' can be an answer for 'prized' (I've seen this before). I'm unsure of the remainder of the definition.

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

Can you help me to learn more?

(Other definitions for treasured that I've seen before include "Darling" , "Cherished, held dear" , "Chersihed, held dear" , "Much-valued" , "Cherished, precious" .)

I've seen this clue in The Times and The Sunday Times.

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