Criminals collared opening night safe initially (4)
I believe the answer is:
cons
'criminals' is the definition.
(short for convicts)
'collared opening night safe initially' is the wordplay.
'initially' says to take the initial letters.
The initial letters of 'collared opening night safe' is 'CONS'.
(Other definitions for cons that I've seen before include "Arguments against" , "Swindles" , "Tricks" .)