Maybe you could strive to eventually be an attorney in entertainment law.
Alternately, you could work as an attorney and write a script
In the evenings and weekends.
Besides those 2 things, I can’t see how you could “combine both.”
I did meet a guy who was an attorney and then eventually quit to write scripts and get into the entertainment industry. His (approx 4th?) script hit pay dirt and he directed the film as well. Was called “the blind side” and was nominated for an academy award.
But had to walk away from a salary as an attorney and jump off a cliff of financial safety.