He's paid to say nothing (5)
I believe the answer is:
extra
'he's paid to say nothing' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
This is the entire clue.
Can you help me to learn more?
(Other definitions for extra that I've seen before include "Player taking little part" , "entry on scorecard?" , "bit-part player" , "Especially" , "I may carry spear" .)