Stay with German article, on balance (9)
I believe the answer is:
remainder
'balance' is the definition.
(I know that balance can be written as remainder)
'stay with german article' is the wordplay.
'stay' becomes 'remain' (synonyms).
'with' means one lot of letters go next to another.
'german article' becomes 'der' (definite article in German).
'remain'+'der'='REMAINDER'
'on' acts as a link.
(Other definitions for remainder that I've seen before include "Surplus" , "Sell off book stock cheaply" , "Residue" , "deposit" , "Balance" .)