Avoiding having a www A REC with BIND9

[Longman]

If you wish to have a domain resolve to the A rec IP of your www host
(and your www host just be a CNAME of this), how would you accomplish
this in BIND? The record can't go in the Zone file for your domain, as
only the hosts/subdomains go in this file? So where does it go?  It
seems to me that it would go at the REGISTRAR level, for they are the
people that provide the 'glue records' for the nameserver addresses of
the domains their servers refer you to, but a bit of googling hasn't
really found much.