He has a heavy role at reading possibly (9)
I believe the answer is:
tragedian
'he has a heavy role' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'at reading possibly' is the wordplay.
'possibly' indicates an anagram.
'at'+'reading'='atreading'
'atreading' with letters rearranged gives 'TRAGEDIAN'.
Can you help me to learn more?
(Other definitions for tragedian that I've seen before include "Egad, I rant about actor in sad drama" , "Egad, I rant about dramatic actor" , "Dramatist" , "A great din (anag) - actor" , "actor in Macbeth?" .)