British islanders (4)
I believe the answer is:
manx
'british islanders' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for manx that I've seen before include "Isle of Man's language" , "The natives' language" , "Kind of cat" , "Sort of cat (from Douglas?)" , "Breed of tailless cat" .)