In law, handrails to be fitted for protection across the country (8,4)
I believe the answer is:
hadrians wall
'protection across the country' is the definition.
(wall built by the Romans)
'in law handrails to be fitted' is the wordplay.
'law handrails' can be anagrammed to 'HADRIAN'S WALL'.
Though, I am unsure how this is indicated.
'for' acts as a link.
(Other definitions for hadrians wall that I've seen before include "Roman fortification across Britain" , "Old border" , "Roman fortification in northern England" , "Solid defence" , "Roman defence against Scots and Picts" .)