It's impossible to say without knowing how she came to have the bare patch. If she's never had feathers there, I wouldn't expect any to sprout. If they are gone from some sort of injury that scarred the skin and damaged the follicles, they won't grow back. If they were plucked because she's being picked on or over-mated, they will grow back if she's separated from the ones pulling her feathers. If they're gone because she's molting, they'll grow back soon.