There should be a little share icon there, but the icon itself is almost white (#EEEEEE) and requires either a dark background or a different color for the icon.
in icons_svg.css
.i-share::before {
content: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' stroke='%23EEEEEE' stroke-width='1px' fill='white' viewBox='0 0 32 32'%3E%3Cpath d='M27 22c-1.4 0-2.7.6-3.6 1.53L9.95 16.8c.04-.27.06-.53.06-.8s0-.53-.02-.8L23.4 8.5c.92.94 2.2 1.52 3.6 1.52 2.76 0 5-2.24 5-5s-2.24-5-5-5-5 2.24-5 5c0 .27.02.54.06.8L8.6 12.52C7.67 11.6 6.4 11 5 11c-2.76 0-5 2.24-5 5s2.24 5 5 5c1.4 0 2.7-.58 3.6-1.52l13.46 6.73c-.04.3-.06.57-.06.8 0 2.8 2.24 5 5 5s5-2.2 5-5-2.24-5-5-5z'/%3E%3C/svg%3E");
}
See that stroke='%23EEEEEE', change it to stroke='%23000000' and you should see it
OR make sure you have the following css class defined in index.css of clean
.container .icon.share {
width: 25px;
padding: .35em .3em .1em .3em;
cursor: pointer;
border-radius: 4px;
}
along with a
.share {
background-color: #008000;
}
in the variant file. That will place a green background there so that almost white EEEEEE icon will show.