### Clue: Key on laptop due to be replaced is of no more use (7,3)
### Answer: CLAPPED OUT 
 ### Explanation: Definition: of no more use
 C(one of the keys in music) **plus**(on) **anagram of**(… to be replaced) LAPTOP DUE.
Defn: Worn out from age or overuse, and hence unable to be used any more.