Possible Clues:

• This membrane lines the nose
• Kind of membrane
• Adjective forbidden in crosswords because it's gross and bodily
• Slimy substance produced in the nose
• Slimy, backward dregs of humanity embracing Open University
• Membrane that lines the nose
• This membrane lines the nose, throat etc
• Of sticky substance that protects inner nose
• There's some work to be done with a shade of the south