A heavy metal; press (4)
I believe the answer is:
iron
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">a heavy metal</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">press</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that press can be written as iron)</span><br/ ><br/ ></span>
(Other definitions for iron that I've seen before include "Metallic element, symbol Fe" , "Press - element" , "Metal (that may be pumped?)" , "Club to smooth the cloth" , "sort of club" .)