Whose performances were as astonishing as all get-out? (7)
I believe the answer is:
houdini
(Other definitions for houdini that I've seen before include "Hungarian-born American magician, d. 1926" , "Harry was famous as an escape artist" , "Famous American escapologist Harry ......." , "Expert at escaping" , "US magician and escapologist, 1874-1926" .)