If I search for WD Clock icon on Google now , all I find a link back to this post. Not useful
curious, anything happen if you right click clock or hover mouse over it? anything apart from open the right click menu on drive anyway. Anything in the menu that show what it might be.
I know apps can change how hdd appear as HD Sentinel adds a Green tick next to drives
I would look in the WD software and see if there is an area in it that lets you change appearance of icon in explorer.