Shakespearean sleepwalker (4,7)
I believe the answer is:
lady macbeth
'shakespearean sleepwalker' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lady macbeth that I've seen before include "Shakespearean female" , "Shakespearean role" , "Ambitious Shakespearean character" , "Tragic figure" , "One promoted queen" .)