Without professional cleaning? If it is male cat spray, you may be doomed. I would try a thick baking soda poultice and let it work for a few days, then do what @johnpowell suggested above. Then I’d apply saddle soap to re-moisturize the leather again, because the baking soda will probably suck out the natural oils that make leather supple. Good luck.
On second thought, before you do anything, call a dry cleaner, or a leather storage warehouse, explain the situation and ask the same question you asked here. It’s worth a shot.
You can’t dry clean leather anyway. I worked at one in high school. We sent leather articles off to someone who specialized in cleaning leather. I have no idea what they did to clean them. It was about a three week turnaround and it was expensive. I’d start by looking at some youtube videos and see if you can’t do it yourself.
It’s not going to happen. Dry cleaning will not help. Cat urine is the worst! Sorry. I threw away a $2500 rug and a Lane leather recliner, both fairly new, because cat had bladder infection and peed on the chair and it ran down onto the rug. That smell was permanent.