Brought up nonsense about performer (5)
I believe the answer is:
Here is my best explanation:
'performer' is the definition.
(actor is a kind of performer)
'brought up nonsense about' is the subsidiary indication.
'brought up' says the letters should be written backwards (down clues only).
'nonsense' becomes 'rot' (I've seen this before).
'about' becomes 'ca' (abbreviation for 'circa'**).
'rotca' backwards is 'actor'.
(Other definitions for actor that I've seen before include "One on stage", "Dramatic artist", "Theatrical performer", "Films/stage worker", "A thespian", "Thespian, stage performer", "Thesp", "Cruise, e.g.", "Player - performer" and "Luvvy".)