Previously, I lamented the lack of an expedient method for renaming sections of a long, digitized clip. We've been using the following method at MediaStorm. WIth your long clip in the timeline, set an in and mark where you'd like the clip to begin and end.
Make sure your playhead is between those two marks and hit F.
The clip with appear in the Viewer with your in and out marks intact. With the Viewer still selected, use the shortcut key command-U to create a subclip.
The new subclip will now appear in the Browser. Rename it accordingly.