Python Pandas. Replace in the column some values with others

The next task is the column BasePay1 . The numbers are indicated in it, but the following values are also found: not provided . So, I need to transform this column to the type float64 .
I do the following: df['BasePay'].astype('float64')
and I get an error: could not convert string to float: 'not provided'
for obvious reasons) the column type BasePay is object
The question is how to replace not provided in the column BasePay with, for example, 0.00? This is the main question) I tried to write functions, nothing helps. I understand that the task is quite easy, but I have been stuck on one spot for 3 hours.