Clean eating simply means avoid processed foods and refined sugars and eat whole foods. Not much really to it other than making good choices.
Clean eating is based on the principle of eating whole, natural unprocessed foods.
Most proponents of clean eating will suggest it is not truly a diet, but rather a view on what to eat and what not to eat.
It focuses on food quality and not quantity, so calorie counting is not utilized in this dietary framework.
On principle, clean eating does not have strict requirements for meal timing or meal frequency (read: how many times a day you eat).
However, in application most clean eating programs suggest people eat 5-6 smaller, clean food, meals and snacks throughout the day rather than 3 main meals.