Begin by navigating to the ClickUp workspace from which you want to export data. Use ClickUp's native export feature to download your data in CSV format. To do this, go to your desired list or space, click on the ellipsis (...) menu, and select "Export" followed by "CSV". Save the file to your local machine.

Open the exported CSV file with a spreadsheet application such as Microsoft Excel or Google Sheets. Inspect and clean the data by removing any unnecessary columns or rows, ensuring data consistency, and verifying that data types align with your Teradata schema. Save the cleaned data as a CSV file.

Access Teradata using a command-line utility like BTEQ (Basic Teradata Query) or a graphical tool such as Teradata SQL Assistant. Ensure you have the necessary credentials and network access to connect to your Teradata database.

In Teradata, create a target table that matches the schema of your cleaned CSV data. Use the `CREATE TABLE` SQL statement to define the table structure, specifying appropriate data types for each column to ensure data integrity.

```sql
CREATE TABLE your_database.your_table (
column1_name column1_datatype,
column2_name column2_datatype,
...
);
```

Use Teradata"s native bulk loading utility such as `TPT (Teradata Parallel Transporter)` or `FastLoad` to import the CSV data into the newly created table. Configure the utility with the appropriate script or command that specifies the input CSV file, the target table, and the data mappings.

Example FastLoad script:
```
LOGON your_teradata_server/your_username,your_password;
DATABASE your_database;
BEGIN LOADING your_table ERRORFILES your_error_table1, your_error_table2;
DEFINE
column1_name (VARCHAR(n)),
column2_name (INTEGER),
...
FILE=my_csv_file.csv;
INSERT INTO your_table VALUES (:column1_name, :column2_name, ...);
END LOADING;
LOGOFF;
```

After loading, run `SELECT` queries in Teradata to verify that the data has been imported correctly. Compare record counts and sample data between the CSV file and Teradata table to ensure accuracy and completeness.

Lastly, document the entire process, including any scripts and configurations used. This documentation will serve as a valuable reference for future data transfers and help in troubleshooting any issues that may arise during the process. Additionally, it can be used to automate the process if needed in the future.

By following these steps, you can effectively transfer data from ClickUp to Teradata without relying on third-party connectors or integrations.