Well what i did was go over to the first tree you can see when you walk into the police fighting area (Joe's house)
anyway go up to the tree and hit it 3-5 times
health packs will fall and food (for the spins) and so will so cats and a safe (no idea why) collect all the packs and food, try to avoid the cats (the safe is just in the tree, it's not important) when your snack level is high just kill the easy people then when it's the swats, dont kill them straight away just run around until the police come. (i know it sounds like it's gonna be hard but it's not)then when they are all together do the spin moves on them, you will probably only need to do it twice as they are all together. and when you've gone onto the 2nd stage of it kill all the kids and mums, a hotdog and a super boost will fall from the sky (COLLECT THEM!!!! you need them to kill the clam)

(i bet i've just ruined the surprise of the 2nd part for you aint i?)