Celtic flower next to hospital (5)
I believe the answer is:
irish
'celtic' is the definition.
(Irish is an example)
'flower next to hospital' is the wordplay.
'flower' becomes 'iris' (iris is a type of flower).
'next to' means one lot of letters go next to another.
'hospital' becomes 'H' (abbreviation for hospital).
'iris'+'h'='IRISH'
(Other definitions for irish that I've seen before include "Native to the Emerald Isle" , "From Cork, for instance" , "race" , "A people, language and whiskey" , "W European" .)