Trial about old play such as King Lear (7)
I believe the answer is:
tragedy
'play such as king lear' is the definition.
'trial about old' is the wordplay.
'trial' becomes 'try'.
'about' indicates putting letters inside.
'old' becomes 'aged' (similar in meaning).
'try' going around 'aged' is 'TRAGEDY'.
(Other definitions for tragedy that I've seen before include "play by Shakespeare?" , "play such as Electra" , "Serious catastrophe" , "Huge blow" , "Sad story" .)