It really doesn't matter if it's a "clean" tear, unless by "clean" it is meant that there were no other ligaments or cartilage damaged during the tear. If there is other damage, then, yes, there's the healing process with that damage as well. When the ACL is repaired, the old ACL is removed completely and a portion of a patella tendon (typically from a cadaver) is used to replace it. So, it really doesn't matter if the ACL is torn clean or ripped to shreds.
I think that he can be ready by October if (1) the surgery goes well; (2) he stays on his rehab (probably not a problem in this case); and (3) he heals quickly. However, I don't know if I would push it because I doubt that even though he may be sufficiently healed by then, can he be effective?