### Clue: Computers use this code when key is sounded (5)
### Answer: ASCII 
 ### Explanation: Definition: Computers use this code
  AS(as in "as and when") + CII{pronounced as a **homophone of**(is sounded) "key"}. 
Answer: Standard code for characters and symbols stored in computers or transferred between computers.  Derived from $$A$$merican $$S$$tandard $$C$$ode for $$I$$nformation $$I$$nterchange.