Don't forget you can trim tracks in iTunes itself...
Do a "get info" on the track in question and go to the "Options" tab and use the "Start time" and "Stop Time" fields to confine Playback between these two points - this method is non-destructive.
If you want to permanently "crop" the track, you can (with the track selected) go to the "Advanced" menu and select "Convert Selection to..."
This will create a "cropped" copy of the track.