Border held by determined Germans (4)
I believe the answer is:
edge
'border' is the definition.
('edge' can be a synonym of 'border')
'held by determined germans' is the wordplay.
'held by' indicates the answer is hidden within the clue.
'EDGE' is hidden in the letters of 'determined germans'.
(Other definitions for edge that I've seen before include "Rim - move gradually" , "Move furtively; intense quality" , "Sharpened side of blade" , "Bind" , "Border - advantage" .)