OnClick Event for Text Box in ASP.NET with C#

I am new to ASP.NET and I was creating a simple form and I wanted to set an OnClick event for a text field so when the user clicked in it, it would clear the text if any was in there. I created the text field and when I click on the Events button in the properties window, it only had the "TextChange" event.  Is it not possible to do OnClick events on text fields using C# in ASP.NET?

Thanks,
~zero
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