It's a fine clue for SHOE but wouldn't be a fine clue for SHOO. The distinction comes down to the word "in" which plays the role of linking word between wordplay and definition. The "I hear" must therefore sit with "go away" (it's the same side of the link word "in"), so it must be a homophone of SHOO.
I thought it was a poor clue. I think the idea is that fall apart is another way of saying apart from a fall, which is analogous to save (except) for (a) trip