Yes, import the address into the single field (for this example let's call it AddressString). Then to split to fields, create your fields (be sure the zip field is text and not number) and then script would be (back up your file first):
Go To Record/Request/Page [ first ]
Set Field [ Street ; GetValue ( AddressString; 1 ) ]
Set Field [ City ; GetValue ( AddressString ; 2 ) ]
Set Field [ State ; GetValue ( AddressString ; 3 ) ]
Set Field [ Zip ; GetValue ( AddressString ; 4 ) ]
Go To Record/Request/Page [ Next ; exit after last ]
Once you have verified that it all worked properly, you can delete the AddressString. Another approach, if you might be concerned about the data at all, is to create calculations out of each of these new fields using the GetValue() calculations provided. Then you can view the data to be sure it all works. Once you know it is okay, just change the fields from calculations to standard text fields. Since the calculations are stored, the data will plant into the fields when you change them and then exit field definitions.
That worked great.
Where can I find a list of functions with their description?
Look up functions in filemaker help.