Prisoner's baccy in tin with refill needed (5)

I believe the answer is:

snout

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But I can't explain it at all! Could you help me understand?

(Other definitions for snout that I've seen before include "nose of pig" , "Porker's hooter?" , "Nose and mouth of a mammal" , "Animal's long, projecting nose" , "Muzzle; Wall (MND)" .)

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