1) PM affair 2) Affair at a salon 3) After-dark gathering 4) After-dinner gathering 5) After-dinner party 6) After-sunset affair 7) Bash in the evening 8) Big do 9) Big function 10) Certain reception 11) Dinner party 12) Do after dark 13) Do in the evening 14) Elegant gathering 15) Elegant reception Found on https://www.crosswordclues.com/clue/soiree
(from the article `Biedermeier style`) ...especially letter writing (giving prominence to the secretary desk) and the pursuit of hobbies. No Biedermeier household was complete without a ... Found on http://www.britannica.com/eb/a-z/s/120
Soi`ree' noun [ French, from soir evening, from Latin serus late, serum late time. Confer Serenade .] An evening party; -- distinguished from levee , and matinée . Found on http://www.encyclo.co.uk/webster/S/138