Apple Final Cut Pro 7 - Manual (Page 109)

Chapter 5 Basic Editing 109
Try This
Create a J-cut, in which the audio precedes the video:
Click the Linked Selection button in the Timeline button bar to turn linked selection off.
1
You can now change the audio and video items of a clip separately.
Linked Selection button
Press R to select the Roll tool. 2
Roll tool
Drag the video edit point at the beginning of Sample Clip 2 forward in the Timeline, as 3
you see in the illustration below.
Drag here with
the Roll tool.
Now the clip’s audio starts before the video.