Or crust and sugar over – (7)
Things crust or sugar over when we neglect them. You know, like when we forget to put the cap back on the honey jar, or when we forget to put things away properly. This simile is interesting, because it makes us think that dreams can last (even you don't act on them) as long as they are properly cared for, properly stowed away. But what does it mean to take care of dreams?
Maybe it just sags (9)
The verb "to sag" makes us think of weight, and lots of it. Why would dreams be associated with weight? Maybe because they are so important and carry a lots of our emotions. Maybe we pack dreams like suitcases, and they grow heavier and heavier over the years until we have to sit on them to zip them up.
Or does it explode? (11)
We don't know what it would mean if a dream were to explode. Would there be little pieces of dreamstuff scattered about like confetti? Would the fire department come? Man, if this is the case, dreams are kind of dangerous.