Hamburgers' rather depleted buns in boxes (4)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

JA (Hamburgers’ rather) + B{un}S (depleted) I mean this clue possibly took me 8 minutes. Part of the problem here may be that, as an American, I don’t really think of ‘rather’ as meaning ‘yes’. And just to spell it out, the first part of this clue refers to how people in Hamburg would say ‘rather’ (in German).