Tune in dance advertisement (6)
I believe the answer is:
ballad
'tune' is the definition.
(type of song)
'dance advertisement' is the wordplay.
'dance' becomes 'ball' (ball is a kind of dance).
'advertisement' becomes 'ad' (short for advert).
'ball'+'ad'='BALLAD'
'in' is the link.
(Other definitions for ballad that I've seen before include "Narrative song of popular origin" , "Love song" , "Simple song or poem" , "Song type" , "Lay, narrative song" .)