The term 'cleared, as a blackboard' can be solved by the word 'erased', which is a six-letter word. Erasing something means to remove it completely, leaving no trace behind. This term is often used in reference to a blackboard, which is a large board made of slate or other material that is used for writing on with chalk. When a blackboard is cleared, all of the writing and drawings on it are erased, leaving it blank.