Volatile liquid formerly used as an anaesthetic (5)

I believe the answer is:

ether

(Other definitions for ether that I've seen before include "Anaesthetic is, strangely, there" , "Formerly an anaesthetic" , "Gas - air - space" , "Anaesthetic; clear sky (poetic)" , "Clear upper air" .)

I've seen this clue in The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.