Go to court, having set fire to one barrier (8)
I believe the answer is:
litigate
'go to court' is the definition.
(I've seen this in another clue)
'set fire to one barrier' is the wordplay.
'set fire' becomes 'lit' (as in lighting a fire).
'to one' becomes 'i' (Roman numeral).
'barrier' becomes 'gate' (gate is a kind of barrier).
'lit'+'i'+'gate'='LITIGATE'
'having' is the link.
(Other definitions for litigate that I've seen before include "Contest at law" , "Dispute by law" , "take action" , "Sue" , "Go to law" .)