Connivance (9)
I believe the answer is:
collusion
'connivance' is the definition.
(I know that connivance can be written as collusion)
This is all the clue.
(Other definitions for collusion that I've seen before include "Secret or illegal conspiracy to deceive" , "Complicity between people for deceitful purpose" , "Illegal co-operation for criminal purposes" , "Secret deception" , "Connivance" .)