If I add a footer to my markup and define a grid-area and place it on the grid using grid-template-areas you can see that it sits below the content column. There is no clearing required as this footer has a track on the grid, it can’t hop up into another track.

Credit to gridbyexample.com for inspiring this example.

[fl_row] {
    display:grid;
    grid-gap: 10px;
    grid-template-columns: 1fr  1fr  1fr;
    grid-template-areas:
    "....... header  header"
    "sidebar content content"
    "footer  footer  footer";
}
[fl_row] .header {
    grid-area: header;
}
[fl_row] .sidebar {
    grid-area: sidebar;
}
[fl_row] .content {
    grid-area: content;
}
[fl_row] .footer {
    grid-area: footer;
}

Header

Content

More content than we had before so this column is now quite tall.

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Suspendisse molestie felis eu mauris aliquet lacinia. Sed fermentum tortor et urna condimentum bibendum. Etiam semper sodales arcu, et elementum turpis volutpat vitae. Mauris fringilla tellus in metus vestibulum iaculis. Proin lacinia velit turpis, in feugiat ex vehicula a. Sed gravida fringilla pretium. Proin quis leo cursus, faucibus quam eu, scelerisque libero. In hac habitasse platea dictumst.

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