Something she could not believe
How could her girl be
So naive
Tar baby, tar baby told
The secret she conceived
Could turn the wind into a song
How could I have doubted
Honey it's with me you belong
I love you so
You cut into my life
Cut through two decades
Like a hot coal on ice
It maybe was meant to be
When I look at you
I can't believe my eyes
I think you just might charm the birds out of the sky
Came good out of grief
That I got caught in
Oh, it's a lover's revenge, but out of the pain
Come the best things you see
You cut into my life (I love you) You cut into my life
You can turn the wind into a song
La la la la la baby baby baby
It's with me you belong

"The Tar-Baby is a doll made of tar and turpentine used to entrap Br'er Rabbit in the second of the Uncle Remus stories. The more that Br'er Rabbit fights the Tar-Baby, the more entangled he becomes. In modern usage, "tar baby" refers to any "sticky situation" that is only aggravated by additional contact. The only way to solve such a situation is by separation. It is considered a racist slur by many." -wiki
Given the above definition, this song is about a unwanted pregnancy of a mother's young daughter. You see, it is very easy to scorn such a situation. Very easy to get upset about it and scream, holler, cry and curse. "How can you be so naive?" -the words reverberate throughout the house
But when the baby is looked upon for the first time, all the pain disappears. Planned or not, legitimate or not, here is a new beautiful life and for as much as you may want to fight it...you cant. So you have no choice but to be "trapped" by this new person. No choice but to love them.
No one asks to be born in this world. So how can any blame be placed on a baby? Nothing left to do but to love them. It is what people do best in-spite of the world's condition.

This song was from her 1985 album Promise - Her only daughter (so far as I can tell) was born in 1996. Get off the heroin thing - the "its always about drugs" thing gets annoying.

It's about how Sade's accidental pregnancy moved her to quit doing Tar (heroin).