Cashels aired and ventilated

• castles in the air: imaginary or unrealistic plans

• cashel: (Anglo-Irish) castle, ring fort, stone fort

• caiseal: (Irish) castle
  • The Castle: Dublin Castle, the centre of British rule in Ireland
  • A Finnegans Wake Gazetteer

• Cashel: a town in County Tipperary; formerly the royal seat of the kings of Munster
  • A Finnegans Wake Gazetteer

• kaszel: (Polish) cough

• clashes → anagram of cashels → see line 1

• aired and ventilated: opinions are aired and ventilated in Parliament.
  • Ironically, there's a conference center today in Dublin Castle, so many opinions are aired and ventilated there nowadays.

• Also, if you unroof a castle, destroying it, it gets "aired and ventilated"

• heard

• vent: (archaic) to utter, to publish

• ventilate: (slang) to shoot with a gun; (of a bullet) to make a hole