### Clue: Doubled up per diem to produce boring talk (4,4)
### Answer: YADA-YADA 
 ### Explanation: Definition: boring talk
 **2x**(Doubled) **reversal of**up …) [A DAY](per diem, as in "a fee of $100 per diem").
Defn: …, probably from "yatata"/idle chatter, in turn from "yatter-yatter"/chatter.