He sings for some rotten orchestra! (5)
I believe the answer is:
tenor
'he sings' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'some rotten orchestra' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'TENOR' is hidden within 'rotten orchestra'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for tenor that I've seen before include "Voice of Tamino" , "thread" , "Male singer with high-pitched voice" , "High male singing voice like Pavarotti" , "Voice classification of Jose Carreras" .)