sys-apps/logwatch-7.1 i added /etc/logwatch/conf/logfiles/clam.conf but logwatch would not load it till i copied that file to /usr/share/logwatch/default.conf/logfiles/ the correct behavior should be where /etc/logwatch is used regardless of what files are in default.conf
this behavior looks like by design ... you should e-mail the logwatch@kaybee.org list to see if they feel like changing it :)
I had the same problem but for two reasons I don't think that "this behavior looks like by design": 1.) It contradicts the description in /usr/share/doc/logwatch-7.1/HOWTO-Customize-LogWatch.gz 2.) It was changed/corrected upstream: logwatch-7.3-r1 behaves like expected and documented.