### Clue: Singers missing parts thrown away by tenor in a state (8)
### Answer: CASTRATI 
 ### Explanation: Definition: Singers missing parts
 CAST(thrown away) **plus**(by) [ T(abbrev. for "tenor") **contained in**(in) RI(abbrev. for Rhode Island, the US state) ].
Defn:  …, those parts required for a donation to 15 down.