Begin by exporting the data from ClickUp. Navigate to the ClickUp workspace and select the project or list you want to export. Click on the "..." (more options) button and select the "Export" option. Choose the format you prefer, such as CSV or Excel, to download your data. Save the file to a known directory on your local machine.

Open the exported file using a spreadsheet application like Microsoft Excel or Google Sheets. Inspect the data for correctness and completeness. Make any necessary adjustments, such as removing unnecessary columns or renaming headers to ensure that they are compatible with DuckDB standards. Save the file in CSV format if it isn’t already.

If you haven't already installed DuckDB, download it from the official DuckDB website (https://duckdb.org/). Follow the installation instructions specific to your operating system. DuckDB is a self-contained, zero-dependency SQL database engine, so installation should be straightforward.

Open your terminal or command prompt and navigate to the directory where you want to create your DuckDB database. Run the command `duckdb mydatabase.duckdb` to create a new database file named `mydatabase.duckdb`. This file will store your imported data.

Launch the DuckDB command-line interface by typing `duckdb` in your terminal. Once in the DuckDB shell, use the SQL command `CREATE TABLE` to define a new table structure that matches the CSV data. Then, use the `COPY` command to load the data. For example:
```sql
CREATE TABLE mytable (
column1 TEXT,
column2 INTEGER,
...
);
COPY mytable FROM 'path/to/your/exported_data.csv' (DELIMITER ',', HEADER);
```
Adjust the table schema and file path as necessary.

After loading the data, verify its integrity by running a few basic SQL queries. For example, you can use `SELECT * FROM mytable LIMIT 10;` to check the first ten rows, ensuring that all data has been imported correctly and is accurately represented.

With your data now in DuckDB, you can perform further analysis or manipulation using SQL queries. DuckDB supports a rich set of SQL features, so you can create advanced queries to analyze your data as needed. Save any changes or results back to the database or export them as required.

By following these steps, you can successfully move data from ClickUp to DuckDB without relying on third-party connectors or integrations.