Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32wb/STM32WB30_CM4/PKA/CLRFR#0x0
PKA clear flag register
Clear PKA End of Operation flag
Clear RAM error flag
Clear Address error flag
https://github.com/modm-io/cmsis-svd-stm32