Cleave for single target?

[Darg]

Benefit: As a standard action, you can make a single attack at your full base attack bonus against a foe within reach. If you hit, you deal damage normally and can make an additional attack (using your full base attack bonus) against a foe that is adjacent to the first and also within reach. You can only make one additional attack per round with this feat. When you use this feat, you take a –2 penalty to your Armor Class until your next turn.

I don't see how there is any room for cleave's second attack to work on your primary target.

Cleave and Vital Strike are separate actions. You do not add both of them together. You use the cleave action and Cleaving Smash allows you to add the extra damage from vital strike. Improved VS = just VS damage. Greater VS = just Improved VS damage. All-Consuming Smash does not add an additional source of extra damage either. Both the trick and the feat add damage from vital strike, so the source is the same. With Greater VS and All-Consuming Smash you'd do 4x weapon damage to the target and 3x damage to an adjacent opponent and yourself.