To clean means to wash something. For example, I cleaned the car, or, I cleaned the cat. To clear means to remove something from a place that is not wanted. For example, I cleared the table (I removed the items from the table), or, I cleared my internet search history (I removed my search entries from my browser history). It can seem confusing in some aspects, such as cleaning/clearing a table. If someone said they cleaned the table, it would usually mean that they have washed the table (as in, washed it with soap and water). If they said they had cleared the table, they would usually mean they have moved the plates and utensils and put them in the sink or dishwasher.