Leave out nothing with German (4)
I believe the answer is:
omit
'leave out' is the definition.
(I know that leave out can be written as omit)
'nothing with german' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'with german' becomes 'mit' ('with' in German).
'o'+'mit'='OMIT'
(Other definitions for omit that I've seen before include "Exclude; veto" , "Leave out, perhaps in error" , "Fail to include" , "Exclude - neglect" , "Leave out or overlook" .)