hangdog expression/look
From Longman Dictionary of Contemporary Englishhangdog expression/lookhangdog expression/lookan expression that shows you feel sorry or ashamed about something I could tell from his hangdog look that things had gone badly. → hangdogExamples from the Corpushangdog expression/look• Ross was still sporting his hangdog look.• He has his father's long face, hangdog expression and lank fair hair.