Synthetic rubber component (7)
I believe the answer is:
styrene
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">synthetic rubber component</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for styrene that I've seen before include "Petroleum by-product used to make plastics" , "hydrocarbon" , "Chemical" , "Component of plastic" .)