Reddish metallic element (6)
I believe the answer is:
copper
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">reddish metallic element</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for copper that I've seen before include "Coin, policeman or metallic element" , "Reddish metallic element" , "Ductile metal" , "Metal - wash basin" , "Low-value coin" .)