def clean_headers(headers):
    """
    Sanitize a dictionary containing HTTP headers of sensitive values.

    :param headers: The headers to sanitize.
    :type headers: dict
    :returns: A list of headers without sensitive information stripped out.
    :rtype: dict
    """
    cleaned_headers = headers.copy()
    authorization_header = headers.get('Authorization')
    if authorization_header:
        sanitized = '****' + authorization_header[-4:]
        cleaned_headers['Authorization'] = sanitized
    return cleaned_headers
