Slow song in party commercial (6)
I believe the answer is:
ballad
'slow song' is the definition.
'ballad' can be an answer for 'song' (ballad is a kind of song). I am unsure of the 'slow' bit.
'party commercial' is the wordplay.
'party' becomes 'ball' (ball is a kind of party).
'commercial' becomes 'ad' (abbreviation for advertisement).
'ball'+'ad'='BALLAD'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for ballad that I've seen before include "Poem telling a story" , "delivered by singer" , "Simple song or poem" , "Folk song" , "Lay, narrative song" .)