Lack of harmony is very new in music for disco (10)
I believe the answer is:
dissonance
'lack of harmony' is the definition.
(I've seen this before)
'is very new in music for disco' is the wordplay.
I cannot quite understand how this works, but
'is' is found in the answer.
'very' could be 'so' (I've seen this in other clues) and 'so' is found in the answer.
'new' could be 'n' and 'n' is located in the answer.
'music' could be 'dance' (dance music is a kind of music) and 'dance' is present in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for dissonance that I've seen before include "Clashing quality of musical notes" , "sounds harsh" , "Discordance" , "quartet?" , "Harsh sound" .)