### Clue: It comes from the Latin, as far as one knows (1,6)
### Answer: A PRIORI 
 ### Explanation: Definition: as far as one knows
  Cryptic defn (I think):  Known to be true without requiring experience or examination of the matter.  The phrase in Latin literally means "(it comes) from the former".  I hope I've got the first part of the clue interpreted correctly – could it perhaps have been better with "It comes from former Latin….."?