Apple Final Cut Pro 7 - Manual (Page 675)

The link between the audio and video in your clip has not been broken, but you can now
trim the audio independently of the video to which it’s linked.
The audio opens in
the Viewer by itself.
3 Select the Selection, Ripple, or Roll tool by clicking in the Tool palette, or by using the
appropriate keyboard shortcut.
4 Set new In and Out points as you would for any other clip.
New Out point set
675 Chapter 43 Audio Editing Basics