Old anesthetic (5)
I believe the answer is:
ether
'old anesthetic' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ether that I've seen before include "Some were put out by this" , "Formerly an anaesthetic" , "Liquid used as anaesthetic/ solvent" , "Colourless, highly flammable liquid" , "Old anaesthetic -- three (anag)" .)