This may tarnish top-notch household cutlery (8,6)

I believe the answer is:

sterling silver

'this may tarnish' is the definition.
(sterling silver may tarnish)

'top-notch household cutlery' is the wordplay.
'top-notch' becomes 'sterling' (both can mean very good).
'household cutlery' becomes 'silver' (silver cutlery).
'sterling'+'silver'='STERLING SILVER'

(Another definition for sterling silver that I've seen is " expensive shiny material".)

I've seen this clue in The Telegraph.

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