Every emergency room has good intensive care for the hypersensitive (8)
I believe the answer is:
allergic
'the hypersensitive' is the definition.
(I've seen this before)
'every emergency room has good intensive care' is the wordplay.
'every' becomes 'all' (similar in meaning).
'emergency room' becomes 'ER' (abbreviation popularized by US TV series).
'has' is a charade indicator (letters next to each other).
'good' becomes 'g' (abbreviation).
'intensive care' becomes 'IC' (abbreviation for intensive care).
'all'+'er'+'g'+'ic'='ALLERGIC'
'for' is the link.
(Other definitions for allergic that I've seen before include "Having unfavourable reaction to, say pollen" , "Hypersensitive to something" , "Responding badly (to something)" , "Reacting badly (to something)" , "Reacting (med.)" .)