The service prints clams without any end in sight.  Looking at the
hint there's bound to be something interesting in that flood near a
`\x0d` character and indeed, it suggests `type "clamclam" for salvation`.

    $ echo clamclam | nc misc.2020.chall.actf.co 20204
    actf{cl4m_is_my_f4v0rite_ctfer_in_th3_w0rld}