One who watches actor step out (9)
I believe the answer is:
spectator
'one who watches' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'actor step out' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'actor'+'step'='actorstep'
'actorstep' anagrammed gives 'SPECTATOR'.
Can you help me to learn more?
(Other definitions for spectator that I've seen before include "member of the crowd" , "I attend sporting event" , "Onlooker at game" , "fan" , "One watching a game" .)