Copy data from Text field to Enum field

I am pulling data from one table to another copying text to text and it works fine.
How do I add a value from a Text field to an Enum field.

This query works fine with Text to Text but breaks with Text to Enum
SELECT(Client[FirstName], ([_THISROW].[ID] =[ID]))

Client[FirstName] is Text that I want to use to Update an Enum how do I cast the type ?

It works fine if by wrapping the query in ANY ANY(SELECT(Client[FirstName], ([_THISROW].[ID] =[ID])))