Last three, but I'm completely stumped:
4d (7): about to enter horse in a sort of heat: Bluey. I have R-D-E-D, so I'm wondering if it's redhead, but why.
5d (4-7): Orthodox writer sent a nib for repair outside. I have B-E-/P-N--T.
23a (9): American Indian woman, announced as Little Ditch. I have M-N-E-A--. I'm wondering if it begins Minne-a--.
Many thanks, as ever, for any help.