Croatian is dressed in a waterproof (8)
I believe the answer is:
raincoat
'a waterproof' is the definition.
('raincoat' can be a synonym of 'waterproof')
'croatian is dressed' is the wordplay.
'is dressed' is an anagram indicator ('dress' can mean 'prepare').
'croatian' with letters rearranged gives 'RAINCOAT'.
'in' is the link.
(Other definitions for raincoat that I've seen before include "Wet weather wear" , "Actor in a (anag) - wet weather garment" , "protection against the elements" , "Protective garment for Croatian" , "Catriona (anag.)" .)