The strange ringtone is gas (8)
I believe the answer is:
nitrogen
'the strange ringtone is gas' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for nitrogen that I've seen before include "It's a gas, the strange ringtone" , "Gas forming about four fifths of the atmosphere" , "Major component of the atmosphere" , "Constituent of four fifths of earth's atmosphere" , "Neon grit (anag.)" .)