Serious actor (9)
I believe the answer is:
tragedian
'serious actor' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for tragedian that I've seen before include "actor in Macbeth?" , "Egad, I rant about actor in sad drama" , "Egad, I rant about dramatic actor" , "Serious actor" , "A great din (anag) - actor" .)