Mark a tin's possibly made? (5)
I believe the answer is:
stain
'mark' is the definition.
(I know that mark can be written as stain)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for stain that I've seen before include "Spot - shame" , "Taint" , "Mark with colour, dirt" , "Stigma" , "Smear" .)