Move under the spinning blades and you'll reach the Sister's ugly body. Turn left. Hit the moving limb a few times to stun it. Quickly use the turnstile when it's not moving. Stun it once more and use the nearby stairs to glide towards the green orb chest. There's a climbable wall nearby. Use it and go along the ceiling to the other side until you get caught by other limb. Free yourself from its grip and destroy the two skeletons that block the grating. Jump down, use the turnstile and reach the upper platform just as you did a moment ago.
You are on a middle level. To get any further, you have to immobilize three of Clothos' limbs. Stun the first one with a few hits, then jump on a nearby rope, climb it up and use the lever to lower the anchor (you have to be quick about it). Go to the next limb - use the lever that will open a small hatch in the floor (don't miss the red orb chest there). Stun the limb and use the lever again to catch it inside the hatch. To immobilize the final limb, grab a mechanism that's positioned near the second one and rotate it counter-clockwise until it's placed under small, metal hands. Stand on the button that's on the mechanism itself (a blade should appear) and stun the final limb. Push the mechanism so that the blade is directly over the limb. Stun it again and you're done. Grab the newly appeared rope and go up.
Clotho stands before you in all her, ahem, glory. You can slow down time freely during this battle. Her hands can be stunned just like the limbs you've dealt with before - use that whenever you need to pass near her unharmed. Go to the right and up the wall, then smash the two skeletons to bits. Grab a handle of a rotating mechanism and push it two segment to the left to position it under a hanging chain. Use the lever in the middle to bring about a giant blade. Rotate it (R1+left analog) and use it (R1). Successfully enter the button sequence and the Sisters of Fate will finally be history.
HINT: You can easily regenerate your health during this boss battle. Use one of the levers to bring in a dead body - Clotho will smash it and thus unload a huge amount of green orbs.
Go through the door at the back of the screen and get upstairs. Dive under the gate. You'll reach a huge, magical mirror. Use the lever to bring up the destiny threads. Run down and choose Kratos' thread (it's a little to the right from the center of the room). Rotate it until you see your battle with Zeus in the mirror. Stop the time and run back to the mirror and jump into it.