Grey alloy (6)
I believe the answer is:
pewter
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">grey alloy</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for pewter that I've seen before include "Beer-tankard alloy" , "prize-money" , "Alloy used for utensils" , "Tin alloy used to make plates and mugs" , "Alloy of tin and lead, often in beer mug" .)