CJ, sticking with the songs about the music biz as opposed to songs about music sub-category, proposes:
I was really struck when reviewing a Lynyrd Skynyrd box set that three years before the Sex Pistols's did "E.M.I." , the Southron boys had recorded a song jibing at their own record company.
CJ also proposes "Punky Reggae Party"
Stanley Whyte suggests these four
Always thought that the Chills one wasn't.... really.... quite.... heavenly enough.... (They've done heavenly-er songs). And then there's the hubris move of putting "hit" in your song title when the chances are that it won't be - ballsy, or foolhardy, who's to say?
"Heavenly Pop Hit" did remind me though of one of my own fave meta-pop songs that also includes the word "heaven" but even more rashly and hubristic-ly includes the word "Number One":
That one does really sound heavenly, to my ears, but is stained somewhat by the humiliation of only having got to Number 14 in the U.K. charts.
The longer version (LP and 12 inch) is sublimer still - the intro section surely an influence on The Associates's "Party Fears Two"?
Talking about heaven, this gorgeous garage classic - a foundational anthem for UKG - celebrates the spiritual power of music via the archangel and his horn.
(Well, of course, the most exciting bit in "Number One Song In Heaven" - the acid-house-a-decade ahead-of-schedule breakdown - is preceded by Russell shrieking: "Gabriel plays it, God how he plays it/ Gabriel plays it, let's hear him play it")
MM nominates "It's All Right" by The Pet Shops Boys.
I actually reviewed Introspective and for a moment almost saw the point of the PSB.
"It's All Right" is a cover version, of course:
(Paris Brightledge, what a name!) (Sterling Void, what a fantastic name!!)
Actually that's not the final guest suggestion, because MM also nominates-
Stop press: Aaron at Airport Through The Trees with a couple of suggestions, including one I'm kicking myself about, because it is pretty much my favorite song-about-music - Sister Sledge's "Lost In Music."
We're lost in music
Caught in a trap
No turning back
We're lost in music
As per Wild Cherry above, Aaron is right to point out that with dance music - disco, funk, house etc - there's a lot of self-reflexive songs - it's music that's about itself most of the time: its own functionality, the behaviour it incites and that it is built for, the community and release it creates, etc etc. There's too many candidates and I almost thought of excluding dance, rave etc from consideration for that reason.
Mind you, especially in the early days, there were a lot of rock'n'roll songs that simply announced the existence, power, and immortality of rock'n'roll. But then that was when rock'n'roll itself was dance music.