Anybody have any advice or tips on transitioning down to one nap?

Miss A is nine months old and her second nap is getting later and later each day resulting in a later bedtime and mondo crankiness in the evening.

We used to have a nice schedule of 7am wakeup, 10-12 nap, 3-4pm nap and 730ish bedtime but lately nap two hasn't been happening till 430ish which means a 10pm bedtime!

I know nine months is on the early side for a single nap but this late bedtime is killing both me and my sanity so any advice would be much appreciated!