### Clue: Ventilate fool admitted to hospital twice in coarse material (9)
### Answer: HAIRCLOTH 
 ### Explanation: Definition: coarse material
 [ AIR(to ventilate;to open to the atmosphere) + CLOT(a fool) ] **contained in**(admitted to) [ **2 x**(… twice) H(abbrev. for "hospital") ].
Defn:  … made from horse or camel's hair, and perhaps human hair – the latter from India: