Found this error when attempting to clean all packages:

eeny:~ osx$ sudo port clean all

[...]

Error: Unable to open port: Package Qt5Core was not found in the pkg-config search path.
Perhaps you should add the directory containing `Qt5Core.pc'
to the PKG_CONFIG_PATH environment variable
No package 'Qt5Core' found

Did a bit of search online and found this macports bug. It explains much more if curious but basically you have to install qt5-qtbase package:

eeny:~ osx$ sudo port -v install qt5-qtbase

[...]

--->  Cleaning qt5-qtbase
--->  Removing work directory for qt5-qtbase
--->  Updating database of binaries
--->  Scanning binaries for linking errors               
--->  No broken files found.                             
--->  Some of the ports you installed have notes:
  dbus has the following notes:
    ############################################################################
    # Startup items have been generated that will aid in
    # starting dbus with launchd. They are disabled
    # by default. Execute the following commands to start them,
    # and to cause them to launch at startup:
    #
    # sudo launchctl load -w /Library/LaunchDaemons/org.freedesktop.dbus-system.plist
    # launchctl load -w /Library/LaunchAgents/org.freedesktop.dbus-session.plist
    ############################################################################

Now the cleanup will be successful!

eeny:~ osx$ sudo port clean all
eeny:~ osx$