Breathe in softly following ether? (4)
I believe the answer is:
gasp
'breathe in' is the definition.
(thesaurus)
'softly following ether?' is the wordplay.
'softly' becomes 'p' (short for piano, musical term for softly).
'following' means one lot of letters go next to another.
'ether?' becomes 'gas' (ether is a gas).
'p' after 'gas' is 'GASP'.
(Other definitions for gasp that I've seen before include "Pant" , "Say "ah"" , "Sudden intake of breath" , "Struggle for breath with open mouth" , "Draw breath sharply" .)