Plotters' group (5)
I believe the answer is:
cabal
'plotters' group' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cabal that I've seen before include "Intrigue, clique" , "Secret political group" , "Secret plot; clique" , "Caucus" , "Intriguing group" .)