Rogue's new name for one working in theatre (7)
I believe the answer is:
surgeon
'one working in theatre' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'rogue's new name' is the wordplay.
'new' is an anagram indicator.
'name' becomes 'n' (common abbreviation e.g. on forms).
'rogues' anagrammed gives 'surgeo'.
'surgeo'+'n'='SURGEON'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for surgeon that I've seen before include "Theatre operator" , "Naval doctor" , "Sawbones" , "Physician" , "Theatre worker" .)