Cartel involved in wine (6)
I believe the answer is:
claret
'wine' is the definition.
(claret is a kind of wine)
'cartel involved' is the wordplay.
'involved' is an anagram indicator (involved can mean confusing or complex).
'cartel' with letters rearranged gives 'CLARET'.
'in' is the link.
(Other definitions for claret that I've seen before include "Dry red wine of Bordeaux" , "English word for red Bordeaux wine" , "Deep purplish colour" , "Dark red Bordeaux wine" , "Wine from the Bordeaux region" .)