Then it should make a method which returns its known, sole entry. Returning a list of entries from a widget which will always contain only one entry is the logical equivalent to converting a function return value to a string and then expecting the client to convert it back from a string. That is to say, it's necessary in a general case (e.g., a Widget super class) but should not be exposed that way in some specific cases (e.g., your subclass wherein you know there will always be one entry).

In reality, you shouldn't be mucking with the entries of a widget at all; you should tell the widget what to do and it should adjust its entries as necessary). Demeter's law and all.