### Clue: Before a judge, fabricating a truth pitilessly? Oh, no — not this! (4,4)
### Answer: UPON OATH 
 ### Explanation: Definition: not this!
A charade of UP ('before a judge') plus ONOATH, an anagram ('fabricating') of 'a t[ruth]' minus RUTH ('pitilessly') plus 'oh no', with an extended definition.