Actor treading out around stage centre (9)
I believe the answer is:
tragedian
'actor' is the definition.
(tragedian is a kind of actor)
'treading out around stage centre' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'around' is an insertion indicator.
'centre' means to look at the middle letters.
The middle of 'stage' is 'a'.
'treading' anagrammed gives 'tragedin'.
'tragedin' going around 'a' is 'TRAGEDIAN'.
(Other definitions for tragedian that I've seen before include "Egad, I rant about actor in sad drama" , "Serious actor" , "A great din (anag) - actor" , "Dramatist" , "Egad, I rant about dramatic actor" .)