Compulsory force or threat (6)
I believe the answer is:
duress
I believe this clue is a double definition.
'compulsory force' is the first definition.
(I've seen this in another clue)
'threat' is the second definition.
(I have seen 'Threat of coercion ' mean 'duress' so perhaps 'threat' could also mean 'duress')
(Other definitions for duress that I've seen before include "Force, coercion" , "Pressure (involving threats)" , "Constraint, Compulsion" , "Hardship" , "Constraint, coercion" .)