Conflict over the German prison officer (6)
I believe the answer is:
warder
'prison officer' is the definition.
(I've seen this before)
'conflict over the german' is the wordplay.
'conflict' becomes 'war' (war is a kind of conflict).
'over' means one lot of letters go next to another.
'the german' becomes 'der' ('the' in German).
'war'+'der'='WARDER'
(Other definitions for warder that I've seen before include "Gaoler" , "screw" , "Jailer" , "Prison officer" , "keeper" .)