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 sign into the type of float64 .
I do the following: df ['Basepay']. Astype ('float64')
and I come out a mistake: could notch to float: 'not provideDed'
for obvious absolutely reasons) type of sign basepay object
the question is how to me in the sign basies not provideDD replace for example at 0.00? This is the main question) I tried to write functions, nothing helps. I understand that the task is quite easy, but I will trample on one revenge on 3 hours.