Cleanness or clarity represent spiritual purity. Cleanliness, in the sense of having been cleansed, signifies one way of getting to that state. Baptism is a ceremony indicative of this.
Psychological / emotional perspective: To be cleaning an article suggests that we are not satisfied with its original state. Making a clear statement suggests a deeply held belief.
Material aspects: When dirty water runs clear or we have a sense of clarity we have an opportunity to clarify misunderstandings and difficulties in everyday life.