From Longman Dictionary of Contemporary Englishworking breakfast/lunch/dinnerworking breakfast/lunch/dinnerBBa breakfast, lunch etc which is also a business meeting → working
Examples from the Corpus
working breakfast/lunch/dinner• The real business gets done at working lunches and small dinner parties.• Gannon explained recently during a working lunch downtown.• The afternoon rehearsal started late because Meredith was at a working lunch in Rose's office.• You might then have a working dinner with a business speaker.• He has working lunches with his team to discuss and develop their approach to managing people for profit. 