### Clue: Don't hold it, because it won't happen (unless you're underwater) (4,6)
### Answer: YOUR BREATH 
 ### Explanation: Definition: Don't hold it, because it won't happen
 Cryptic defn: From the phrase "Don't hold your breath"/to tell someone that they shouldn't have any hope of something happening, because it won't happen. On the other hand, you do want to, literally, hold your breath when you're underwater.