Tragic Shakespearian king (4)
I believe the answer is:
lear
'tragic shakespearian king' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lear that I've seen before include "Playful king and writer of nonsense verse" , "Tragic character" , "King -, Edward -" , "A real playful king" , "of poetry?" .)