### Clue: Start of theme song writer is breaking into as drink is served? (3,5)
### Answer: TIA MARIA 
 ### Explanation: Definition: drink is served
 [ **The 1st letter of**(Start of) "theme " + ARIA(a solo vocal piece with instrumental accompaniment, as in an opera) ] **containing**(… breaking into) [I AM]("the writer is", self-referentially).