Hi Tony, not sure what you mean by 'clean'. If you mean the timing is not right, you can increase the resolution of the jog wheel by pressing the Jog Play button and using the cursor buttons. You should be able to get down to approx. 3ms accuracy. If you mean there's a click at the join point, the waveform display (also via Jog Play) should help to locate the loop point to some point in the audio where any clicks will be masked. The track edit operations are very quick and can be undone, so you can keep tweaking the time markers until you get it spot on.
Update: you'll need the display set to Absolute time to see resolutions down to 3ms (actually 1/10th frame, where there are 30 frames per second). If it's showing beat & bars, you won't see this.