Channel Five breaking ground rule in court (7)
I believe the answer is:
culvert
'channel' is the definition.
(culvert is a kind of channel)
'five breaking ground rule in court' is the wordplay.
'five' becomes 'V' (Roman numeral).
'breaking' is an insertion indicator.
'ground' indicates an anagram ('grind' the letters into a new form).
'in' indicates putting letters inside.
'court' becomes 'ct' (abbreviation used in road names).
'rule' with letters rearranged gives 'uler'.
'v' placed inside 'uler' is 'ulver'.
'ulver' placed inside 'ct' is 'CULVERT'.
(Other definitions for culvert that I've seen before include "Tunnelled drain for water" , "Drain channel" , "Drainage tunnel" , "Drain tunnel" , "Water channel" .)