Reference sees head replaced by company complicity (9)
I believe the answer is:
collusion
'complicity' is the definition.
(I've seen this before)
'reference sees head replaced by company' is the wordplay.
I cannot really understand how this works, but
'company' could be 'co' (abbreviation) and 'co' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for collusion that I've seen before include "Secret deception" , "Secret or illegal conspiracy to deceive" , "Illegal co-operation for criminal purposes" , "Complicity between people for deceitful purpose" , "Connivance" .)