The German girl has a key (3)
I believe the answer is:
die
'the german' is the definition.
('the' in German)
'girl has a key' is the wordplay.
'girl' becomes 'di' (**).
'has' is a charade indicator (letters next to each other).
'a key' becomes 'e' (I've seen this in other clues).
'di'+'e'='DIE'
(Other definitions for die that I've seen before include "Pass away" , "Cease living" , "Device that stamps design on metal" , "THIRD PART OF 24" , "Give out" .)