### Clue: Keep quiet about silver and nitrogen in the bottle (6)
### Answer: MAGNUM 
 ### Explanation: Definition: bottle
  MUM(keep quiet) **containing**(about) AG(symbol for the element silver in chemistry) **plus**(and) N(similarly for the element nitrogen)
Defn: A large bottle (for wine) whose capacity is that of 2 ordinary bottles, or 1.5 litres