Sn on the periodic table (3)
I believe the answer is:
tin
'sn on the periodic table' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tin that I've seen before include "roofing material" , "1 down, symbol Sn" , "Element, symbol Sn" , "A silvery-white metal often in cans" , "Kind of metal often used as food container" .)