Hi, a slight limp is usually no big deal for a cat. It might indicate a strained tendon. If it were a broken bone, she would not walk on the leg at all. When you are looking at her foot, also look at her leg for any possible bites, and also feel her shoulder. So far, it doesn't sound bad. But if you happen to find a bite, get her in to see the vet as soon as possible. Cats' skin can close around a puncture wound before it bleeds enough to clean out infection, and a cat can get very serious abscesses from bites (especially from other cats). If you are feeling along her foot and all the way up the leg to the top, she doesn't seem too bothered (such as, she doesn't his at you and run away), she probably is dealing with a slight muscle or tendon strain and not a bite. Watch and check her every few hours for a couple of days at least. If it's a strain, she will get better. If it's an abscess, she will get worse and it will be a serious deal pretty fast.
Regarding the apparently missing claws, do you know her whole veterinary history? I don't want to seem too basic, but starting at the beginning -- unlike a dog, a cat can retract her claws so you don't see them. If you are fully aware of this and can make her extend her claws by pressing on the underside of her toes, and you can tell she genuinely doesn't have claws on that foot, does she for some reason have claws on all her other feet?
If both front feet have no claws that extend when you push under her toes, it's possible that sometime in her past she was declawed. But no vet would ever do that only to one foot. (And if the foot you are concerned about is a rear foot, rear feet aren't declawed anyway.) Declawing is done on both front feet, and it is rarer to see a declawed cat than it used to be, because fewer and fewer vets will even do that cruel operation. (It involves removing the whole front knuckle of the toe, and it also makes the cat unsafe if she gets out and has to fend off a predator.) Because it would be WILDLY unusual for a cat to be declawed on only one foot, that makes me think you are guessing wrong when you say the cat has no claws on just that foot alone.