Only show menu icon (hide the text)

Never mind. Already found out how to do this. The base of it is this code:

    .menu-icon-only a {
        visibility: collapse;
    }

    .menu-icon-only a span {
        visibility: visible;
    }

Use the class menu-icon-only on your wordpress menu-item where you want to show only the menu icon. It might need some extra attributes to adjust some paddings, margins, height etc.. Depends on your menu styling.