### Clue: Let sleeping dogs lie, say, when one's restrained by lead (7)
### Answer: PROVERB 
 ### Explanation: Definition: Let sleeping dogs lie, say
  ROVER(a traditional name for a dog, one that is sleeping or not) **contained in**('s restrained by) PB(the chemical symbol for the element, lead).  A doggy surface.
Answer:  An example of which;say, is "Let sleeping dogs lie ".