Royal flush component (3)
I believe the answer is:
ace
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">royal flush 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 ace that I've seen before include "1" , "single > club > champion" , "strained" , "Expert (sl.)" , "One or 11 in cards" .)