No need to define the selection color for the clock

common/gnome-shell/3.30/sass/_common.scss

@@ -144,7 +144,7 @@ StScrollBar {
   -barlevel-active-background-color: $selected_bg_color;        //active trough fill
   -barlevel-active-border-color: transparentize(black, 1);      //active trough border
   -barlevel-overdrive-color: $destructive_color;
-  -barlevel-overdrive-border-color: transparentize(black, 1); 
+  -barlevel-overdrive-border-color: transparentize(black, 1);
   -barlevel-overdrive-separator-width: 1px;
   -barlevel-border-width: 0;
   -slider-handle-radius: 0px;
@@ -1009,7 +1009,6 @@ StScrollBar {
   .screencast-indicator { color: $error_color; }
 
   .clock-display > * > *:last-child {
-    color: $selected_fg_color;
     margin-left: .3em;
   }
 
@@ -1319,17 +1318,17 @@ StScrollBar {
     > StIcon {
       icon-size: 18px;
       border-radius: 0px;
-      color: transparent; 
+      color: transparent;
       background-color: transparent;
       background-image: url('#{$asset_path}/misc/message-close.svg');
     }
     &:hover > StIcon {
-      color: transparent; 
+      color: transparent;
       background-color: transparent;
       background-image: url('#{$asset_path}/misc/message-close-hover.svg');
     }
     &:active > StIcon {
-      color: transparent; 
+      color: transparent;
       background-color: transparent;
       background-image: url('#{$asset_path}/misc/message-close-active.svg');
     }
@@ -2172,7 +2171,7 @@ $legacy_icon_size: 24px;
   &:active, &:checked { @include button(osd-active); }
 
   &:grayed { @include button(osd-insensitive); }
-}                             
+}
 
 .keyboard-subkeys { //long press on a key popup
   color: $osd_fg_color;