I think if you ask 100 different people, you will get 100 differerent answers.
I personally hate the term "clean eating." I prefer "whole-foods-plant-based diet."
Don't sweat the small stuff. I see a lot of posts where people seem almost paranoid about eating clean or not eating clean. It's how you eat the majority of the time, consistently, that determines your level of health, not every single morsel that goes into your mouth.
As for your particular questions: IMO, canned beans are fine, as long as you drain and rinse them, to get most of the added salt off. Eating canned beans is better than eating no beans, and many people don't have time to cook them from dry, so canned is a good alternative.
Frozen veggies and fruits are fine, and in fact, when foods are not in season or don't grow in your particular area, they often have more nutrients in than "fresh" foods.
Frozen or canned meat substitutes can have a lot of processed foods in, particularly protein isolates or concentratesl. IMO, they are not whole/clean foods, but making them a small part of your diet isn't a big problem. (There are no "clean eating police" who will come and slap the cuffs on you if you dare eat them!)
As for Splenda, I don't consider it to be a food, but a chemically-manipulated sugar. I won't have it, or any other artificial sweetener.
From your last sentence, it sounds like you are mostly looking to lose or maintain weight. In that case, emphasize fresh or minimally prepared veggies, fruits, whole grains. Avoid foods withh chemicals in, processed foods, stay away from high fructose corn sweetener and hydrogenated oils (two "created" foods whose increase in consumption correlates almost exactly with the increase in obesity and overweight in the US.)