After a dance composing sad songs (7)
I believe the answer is:
ballads
'songs' is the definition.
(I know this)
'after a dance composing sad' is the wordplay.
'after' means one lot of letters go next to another.
'a dance' becomes 'ball' (ball is a kind of dance).
'composing' is an anagram indicator.
'sad' anagrammed gives 'ads'.
'ball' next to 'ads' is 'BALLADS'.
(Other definitions for ballads that I've seen before include "Popular songs" , "Soppy songs!" .)