Blackmail tactic (6)
I believe the answer is:
threat
'blackmail tactic' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for threat that I've seen before include "Statement of intention to harm" , "Possibility of danger" , "Expression of intention to harm" , "Statement of intent to do harm" , "Declaration of intention to harm another" .)