If the recipe writer is following standard publishing conventions, he or she is calling for a whole pound of clarified butter, so you'd need to start with one-and-a-quarter pounds or so of regular butter. If he or she meant the weight before clarification, the recipe should say "one pound of butter, clarified."

The problem is, many recipe writers (and more than a few cookbook editors and publishers) don't grasp many of the conventions that have sprung up to make recipes consistent and easy to follow. We are not necessarily fans of a deadly cookie-cutter approach to writing recipes, but you can quickly tell which books have come from publishers who know what they are doing and from those who don't. Even books with real personality, a strong voice, or a great sense of place adhere to certain conventions that make their recipes easy to follow. That can be a real problem with Internet recipes, though, and those from your Great-Aunt Mabel, because sometimes the directions are just not clear.

Your recipe writer may be expecting you to purchase clarified butter, but most people we know make it when they need it (or they skip it entirely and move on to another recipe) (more's the pity).