Such surgery scares a lot — not all coming back (5)
I believe the answer is:
laser
'such surgery' is the definition.
'laser' can be an answer for 'surgery' (thesaurus). I'm unsure of the 'such' bit.
'scares a lot not all coming back' is the wordplay.
'not all' says the answer is hidden in the clue.
'coming back' says the letters should be written backwards.
'resal' is hidden within 'scares a lot'.
'resal' in reverse letter order is 'LASER'.
Can you help me to learn more?
(Other definitions for laser that I've seen before include "Device producing an intense light beam - kind of sailing dinghy" , "modern light industry" , "type of surgery" , "Scientific apparatus" , "E.g. surgical light-beam" .)