Complex whole (6)
I believe the answer is:
system
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">complex whole</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for system that I've seen before include "Organised structure for arranging or classifying" , "Organised method" , "My sets (anag.)" , "Set of things in a connected whole" , "Body of doctrine - method of procedure" .)