Song and dance followed by commercial (6)
I believe the answer is:
ballad
'song' is the definition.
(ballad is a kind of song)
'dance followed by commercial' is the wordplay.
'dance' becomes 'ball' (ball is a kind of dance).
'followed by' means one lot of letters go next to another.
'commercial' becomes 'ad'.
'ball'+'ad'='BALLAD'
'and' is the link.
(Other definitions for ballad that I've seen before include "Slow sentimental song" , "delivered by singer" , "Narrative song of popular origin" , "Song that tells a story" , "Lay, narrative song" .)