Element of ringtone jangled (8)
I believe the answer is:
nitrogen
'element' is the definition.
(chemical element)
'ringtone jangled' is the wordplay.
'jangled' is an anagram indicator (letters jangle around).
'ringtone' with letters rearranged gives 'NITROGEN'.
'of' acts as a link.
(Other definitions for nitrogen that I've seen before include "Atomic number 7" , "Common gas, N" , "Gas forming about four-fifths of atmosphere" , "Main element of air" , "Major constituent of air" .)