18month old wakening at 5am

Hi everyone, any tips on how the get my toddler to sleep in. Shes 18months and has been wakening every morning for the past 2 months at 5am. She takes a nap in the day around 12-1. And she is exhausted. Shes cranky when she wakens in the mornings and cranky after her nap because she hasnt slept long enough. She goes to bed around 7/7.30. I Tried a later bed time, no screen time and shes always outside in the fresh air. But nothing seems to help