move spaces to a given column via worksheet command

You can do this easily in Excel without anything advanced. To protect the sheet, select the whole worksheet, open Format Cells, go to Protection, and keep Locked enabled, then select only the column your wife uses and uncheck Locked for that column. After that, go to the Review tab and choose Protect Sheet to lock everything except her input column. When she finishes entering her food, you can simply select that column and press Delete to clear it. If you want it to clear automatically, that would require a macro, but the manual method is the safest and simplest.