Criminal once more losing nothing -- he often argued with the court's judges (7)
I believe the answer is:
mcenroe
'he often argued with the court's judges' is the definition.
(John McEnroe argued with tennis umpires a lot)
'criminal once more losing nothing' is the wordplay.
'criminal' is an anagram indicator.
'losing' indicates named letters should be taken away.
'nothing' becomes 'O' (O resembles 0).
'once'+'more'='oncemore'
'oncemore' with 'o' removed is 'ncemore'.
'ncemore' is an anagram of 'MCENROE'.
(Other definitions for mcenroe that I've seen before include "John --, US tennis player" , "he's noted for being controversial" , "Tennis star" .)