Kentucky law says you have to draw a seat within Jefferson County. I'm not sure what the most-Republican version of that seat looks like, or whether it's even possible to draw a Trump-voting CD in JeffCo (I imagine not, though by sinking the black parts with rural areas you can probably get a much redder seat than the one that currently exists).
The seat can't be cracked unless they change state law, which Beshear won't let them do. (Had Bevin won, it probably would have been cracked). But they can certainly unpack it to some extent.
Can Beshear actually block it with only a majority needed for a veto override? It's probably not happening though since the support isn't there amongst legislative leaders regardless. I think the key issue is no Republican incumbents want a significant portion of Louisville in their district.