Romantic song everyone gets nasty about (6)
I believe the answer is:
ballad
'romantic song' is the definition.
(I've seen this before)
'everyone gets nasty about' is the wordplay.
I cannot really understand how this works, but
'everyone' could be 'all' (I've seen this before) and 'all' is found within the answer.
'about' could be 'a' (abbreviation in Chambers) and 'a' is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ballad that I've seen before include "Narrative poem or song" , "delivered by singer" , "Narrative song with a recurrent refrain" , "Poem telling a story" , "Form of verse" .)