Queen Boudicca's tribe (5)
I believe the answer is:
iceni
'queen boudicca's tribe' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for iceni that I've seen before include "Boadicea's tribe" , "Ancient tribesmen" , "Ancient British tribe" , "Old warriors" , "Old people" .)