If it's only a slight clay odor, then it should be completely ok to
use. It takes a long time for the clay odor to go away. I woudn't
leave spent tea leaves in the teapot for too long. It could sour the
pot - give off a funky odor that's hard to get rid of. But you can
drench your teapot in tea rinse each time you brew the same tea.
Drench inside and out; then pour dry. Then say, after several months,
the teapot will be ready to use. You should have separate tea towels
(highly absorbent ones are best); and reserve those only for tea use.
Wash and dry separately from other laundry. You can use a tea towel to
buff the exterior of the teapot.