Dangerous having no hospital open (4)
I believe the answer is:
airy
'open' is the definition.
(both can mean spacious)
'dangerous having no hospital' is the wordplay.
'dangerous' becomes 'hairy' (I've seen this before).
'having no' is a deletion indicator.
'hospital' becomes 'H' (abbreviation for hospital on maps).
'hairy' with 'h' taken out is 'AIRY'.
(Other definitions for airy that I've seen before include "Well-ventilated; delicate" , "Delicate; well ventilated" , "Well ventilated; insubstantial" , "Old astronomer" , "Open and spacious" .)