Add styling for clear icon

src/definitions/modules/dropdown.less

@@ -925,6 +925,18 @@ select.ui.dropdown {
 }
 
 
+/*--------------------
+        Clear
+----------------------*/
+
+.ui.dropdown > .clear.dropdown.icon {
+  opacity: @clearableIconOpacity;
+  transition: opacity @defaultDuration @defaultEasing;
+}
+.ui.dropdown > .clear.dropdown.icon:hover {
+  opacity: @clearableIconActiveOpacity;
+}
+
 
 /*--------------------
         Disabled

src/themes/default/modules/dropdown.variables

@@ -211,7 +211,7 @@
 @selectionActiveHoverMenuBoxShadow: @selectionVisibleMenuBoxShadow;
 
 @selectionVisibleConnectingBorder: 0em;
-@selectionVisibleIconOpacity: 1;
+@selectionVisibleIconOpacity: '';
 
 /*--------------
      Search
@@ -309,6 +309,10 @@
 @errorItemHoverBackground: #FFF2F2;
 @errorItemActiveBackground: #FDCFCF;
 
+/* Clearable */
+@clearableIconOpacity: 0.8;
+@clearableIconActiveOpacity: 1;
+
 /*-------------------
       Variations
 --------------------*/