The crossword clue ‘Half of a leaf’ is referring to a specific term used in bookbinding and printing, which is ‘recto‘.
Recto is the term used to describe the right-hand side of a book or a printed page, typically the front side. In bookbinding, a leaf refers to one piece of paper that has been folded in half, which creates two sides, the recto on the right and the verso on the left.
Recto is derived from the Latin word meaning “right,” and it has been used for centuries in the bookbinding and printing industries. The recto side of a page is considered the “front” side because it is typically the first side that people see when opening a book or reading a document.
In summary, ‘recto‘ is the term used to describe the right-hand side of a printed page or the front side of a leaf in bookbinding.