Good summary, scola. And a lovely clue from Swowl!
My tiers:
Ivory, snow
Antarctica, mail
Whale, dice, pizza, snake
Is there some significance to clue being whitish, not white? Like, maybe the band Whitesnake is less likely because it's not really whitish in any way? Also pizza isn't really whitish, that's just white pizza. Moby Dick is the "white whale", though perhaps also whitish in color (same for the terrible tasting type pizza though, hmm).
I would go ivory -> snow -> antarctica -> mail -> dice. But it's very close after the first four. This is such a great clue, should give us a lot of information in the later rounds even if we don't get them all at once here. A problem with dice is that if you don't think about it, you might not make the connection to them usually being white. Same goes for pizza. I feel pretty good about the first four (ivory snow antarctica mail).