viewing source timecode of clip on timeline (project in fcp x)

The command for match frame is SHIFT+F, which reveals the clip and selection range in the browser.
Also, if you skim over your clip in the timeline with the trim tool selected (instead of the selection tool) you will see the clip timecode. My trick is to hold down T without letting go to temporarily engage the trim tool. Blade and Range tool do the same thing

Check out Richard Taylor's Tips. that's where I discovered the above.

Try the "Clip Skimming"-command under the View menu. Should show you the TC if there is one.