A metallic element (6)
I believe the answer is:
metals
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a metallic element</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that metallic element can be written as metals)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for metals that I've seen before include "Gold and silver, say" , "Copper, tin and iron" , "Silver and aluminium, say" , "Silver and platinum, say" , "Such as iron, gold, etc" .)