The only thing I can think of is maybe the bearings aren't seated properly. Also, isn't the end of the axle stub on yours threaded? I've had to thread bolts into the end of a couple other vehicles before to yank the axle stub out enough. This may be a case of the old "take apart, put together again, and the problem goes away"
The clip is actually needed, it keeps the axle shaft poking out enough to engage into the drive flange. The wheel won't fall off since that's retained by the big spindle nut, but you might end up with no power hitting the pavement if it slips out and starts spinning.
My oil line fix
My 100k stopped odometer fix
Brace for impact, I'm in a "modifying mood". Massive thread count inbound.