Steelie alternative (5)
I believe the answer is:
agate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">steelie alternative</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for agate that I've seen before include "Quartz gem" , "Hard stone with concentric bands of colour" , "Stone with coloured bands" , "Quartz with bands of colour, used in jewellery" , "Old drama critic" .)