spick and span
Totally clean and/or organized. I plan to spend the day cleaning so that this place is spick and span when my mother-in-law arrives.
spic and span
Neat and clean. A “spick” was a nail (as in “spike”), “span” was a wood shaving, and a new wooden object had shiny spicks in it and fresh spans around it. Over the years the meaning of newness was replaced by that of something fresh and clean (as a new object usually was).