Strike-breakers restrain lawyers by day — might they be carrying swords? (9)
I believe the answer is:
scabbards
'might they be carrying swords?' is the definition.
(a scabbard is a sheath for a sword)
'strike-breakers restrain lawyers by day' is the wordplay.
'strike-breakers' becomes 'scabs' (workers who refuse to join a strike).
'restrain' is an insertion indicator.
'lawyers' becomes 'bar' (I've seen this before).
'by' is a charade indicator (letters next to each other).
'day' becomes 'd' (abbreviation for day).
'bar'+'d'='bard'
'scabs' going around 'bard' is 'SCABBARDS'.
(Other definitions for scabbards that I've seen before include "Sheaths for swords or daggers" , "Sheathes for swords, daggers" , "Blade covers bard's cabs" .)