CLEARLY we must invent a new gismu for this!I propose {bleni} because "Blah!" for how you react to this suggestion, and then it also sounds like "any".
On a more serious note, I think a clear-cut PA would be very handy.
- Which one? There are several in this basket.
- Any. I want to eat.
I think logic can't define the difference between "one of..." and "any". There for {xe'e} in PA would be strange.
What are your objections against {su'a}?
{da} - some apple in the basket.
{da su'a} - any apple in the basket.
{da su'anai} - some specific apple in the basket (e.g. the yellow one).