Appalling as many a Shakespeare drama (6)
I believe the answer is:
tragic
'appalling' is the definition.
(tragic can mean horrible or appalling)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for tragic that I've seen before include "Intensely sad and distressing" , "Pathetic" , "'Very, very sad (6)'" , "Heart-rending" , "Very sad; Schubert's 4th symphony nickname" .)