This trophy asks you to clear one track on the far side, then clear a track on the opposite side. So if you clear the track on the far left side, you have to switch to the far right and vice a versa. It sounds a bit tough, but actually there's a really easy trick to it.
As you progress through songs, you'll hit checkpoints which clear the screen for a moment. This gives you a great chance to move freely between each side and earn this trophy. So just clear a far side before a checkpoint, enter it and then immediately move to the opposite side and this will unlock during gameplay. Can be done on any song, campaign or quickplay.