Great Trek participant (4)
I believe the answer is:
boer
'great trek participant' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for boer that I've seen before include "South African inhabitant" , "Robe worn by S African rebel" , "South African descended from Dutch settlers" , "Dutch settler in southern Africa" , "one from East London perhaps" .)