Highland tribe (4)
I believe the answer is:
clan
'highland tribe' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for clan that I've seen before include "(Scottish) family group" , "Scots family grouping" , "Macdonald, perhaps" , "People related by blood and marriage" , "Tribe or collection of families under a cheiftain" .)