Bill's extra procedure in court accusation (7,6)
I believe the answer is:
service charge
'bill's extra' is the definition.
(extra charge on a restaurant bill)
'procedure in court accusation' is the wordplay.
'procedure in court' becomes 'service' (service on a tennis court).
'accusation' becomes 'charge' (I've seen this before).
'service'+'charge'='SERVICE CHARGE'
(Other definitions for service charge that I've seen before include "it may mean that extra 10%" , "Percentage added to the bill?" , "Restaurant bill addition" , "Addition to diner's bill" , "Amount added to a bill in a restaurant" .)