Possibly writing your own encryption & decryption functions. That way, you can select which fields needs to be encrypted.
If you use the ABC version of Clarion, you could add your code to the .Insert, .TryInsert, .Update, .Fetch, .Tryfetch, .Next, .Previous, etc methods in the global FileManager objects of the Tables to take care of the automatic encryption & decryption of data.
Adding TPS encryption on top of that will give you a double protection.