Restraint of Roman soldiers suppressing resistance (3-4)
I believe the answer is:
leg-iron
'restraint' is the definition.
(a shackle on a leg)
'roman soldiers suppressing resistance' is the wordplay.
'roman soldiers' becomes 'legion' (group of soldiers in Ancient Rome).
'suppressing' indicates putting letters inside.
'resistance' becomes 'r' (electronics abbreviation).
'legion' going around 'r' is 'LEG-IRON'.
'of' is the link.
(Other definitions for leg-iron that I've seen before include "Ankle restraint for a prisoner" , "Fetter" .)