Surgery alternative? About time (9)
I believe the answer is:
operation
'surgery' is the definition.
(I know that surgery can be written as operation)
'alternative? about time' is the wordplay.
'alternative?' becomes 'option' (synonyms).
'about' means one lot of letters goes inside another.
'time' becomes 'era' (an era is a period of time).
'option' enclosing 'era' is 'OPERATION'.
(Other definitions for operation that I've seen before include "management" , "financial transaction" , "military undertaking" , "working" , "activity" .)