Hard metal element (7)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hard metal element</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 iridium that I've seen before include "number 77" , "Silvery-white metallic element" , "Colourful compounds come from this" , "Hard metal element, Ir" , "Metallic element resistant to corrosion, atomic no. 77" .)
(Other definitions for tantalum that I've seen before include "Acid-resistant metal" , "Metallic element, symbol Ta" .)