Secret plot (6)
(Other definitions for scheme that I've seen before include "Design" , "Project or strategy" , "Lay plans" , "Machination" , "Plan - intrigue" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">secret plot</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 cabal that I've seen before include "Small party" , "Secret plot or the people engaged in it" , "Clique of plotters" , "Plotting group" , "Secret plot; clique" .)