Seal tins contaminated with second type of steel (9)
I believe the answer is:
stainless
'type of steel' is the definition.
'seal tins contaminated with second' is the wordplay.
'contaminated' indicates anagramming the letters (a corrupted spelling).
'with' means one lot of letters go next to another.
'second' becomes 's' (common abbreviation).
'seal'+'tins'='sealtins'
'sealtins' with letters rearranged gives 'stainles'.
'stainles'+'s'='STAINLESS'
(Other definitions for stainless that I've seen before include "Resistant to marking" , "Squeaky-clean" , "Without blemish" , "This steel contains chromium" , "Without colour" .)