Shackles made by strike-breaking workers (9)
I believe the answer is:
handcuffs
'shackles' is the definition.
(handcuff is a kind of shackle)
'strike-breaking workers' is the wordplay.
'strike' becomes 'cuff' (I've seen this before).
'breaking' is an insertion indicator.
'workers' becomes 'hands' (hand is a kind of worker).
'cuff' going into 'hands' is 'HANDCUFFS'.
'made by' acts as a link.
(Other definitions for handcuffs that I've seen before include "Restraining devices" , "result in restriction of movement" , "Prisoner restraints" , "Police links" .)