Elect to have surgery on time (3)
I believe the answer is:
opt
'elect' is the definition.
(I've seen this in another clue)
'surgery on time' is the wordplay.
'surgery' becomes 'op' (short for operation).
'on' means one lot of letters go next to another.
'time' becomes 't' (abbreviation).
'op'+'t'='OPT'
'to have' acts as a link.
(Other definitions for opt that I've seen before include "Hold in the highest esteem" , "Choose from pot" , "Prefer, choose" , "Make a choice" , "End or act of shutting" .)