Premiere Pro doesn't have one, I believe. I really wish it did.
You can place your playhead and then use your mouse to select your clip. Then use Commadn+X to cut (Control+X in Windows). And then, use Command+V to paste the begging of the clip at the playhead, which will perform an overwrite edit. The clip will be pasted on to whatever track you have targeted.
If you want a cool third-party extension and have a little money to spend, I can recommend the Excalibur Premiere Pro extension, which has commands to move the beginning or the end of a clip to the playhead.