Tin-filling method demonstrated (5)

I believe the answer is:
shown
'demonstrated' is the definition.
(I've seen this before)
'tin-filling method' is the wordplay.
I cannot really understand how this works, but
'method' could be 'how' (I've seen this in another clue) and 'how' is present in the answer.
'tin' could be 'sn' (Sn is the chemical symbol for tin) and 'sn' is found in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for shown that I've seen before include "Displayed" , "Exhibited" , "Explained" , "Demonstrated" .)
