Some chose the right anaesthetic (5)
I believe the answer is:
ether
'anaesthetic' is the definition.
(ether is a kind of anaesthetic)
'some chose the right' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'ETHER' is hidden in the letters of 'chose the right'.
(Other definitions for ether that I've seen before include "Formerly an anaesthetic" , "Light liquid used as anaesthetic" , "Medium supposedly" , "There goes the anaesthetic" , "The gas is there, oddly" .)