Run ST_DWithin on a subquery result from a different table

I have two tables "Customers", and "Providers" in my PostgreSQL DB. They both have a ‘geom’ column. Now, customer Table has a column called e.g. "profession".

I want to get the COUNT of providers from "Providers" table within 1000m from all the customers in the "Customers" table, where e.g. "profession" = "GIS Developer"

Even better, I’d like to have a function called e.g. _getCustomersStats(profession)

So I can call it like this: SELECT * FROM public._getCustomersStats(‘GIS Developer’)

and get this result:

I’ve tried this query bellow. I haven’t gotten to creating the function yet because this query is not working for me:

with
    cust as (
    select
        *
    from
        Customers as c
    where
        c.profession = 'GIS Developer'
    ),
select
    count(*)
from
    cust, Providers as p
where
    ST_DWithin (cust.geom, p.geom, 1000)