European - one seen with the German duck (5)
I believe the answer is:
eider
'duck' is the definition.
(eider is a type of duck)
'european one seen with the german' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'one' becomes 'i' (Roman numeral).
'seen with' means one lot of letters go next to another.
'the german' becomes 'der' ('the' in German).
'e'+'i'+'der'='EIDER'
(Other definitions for eider that I've seen before include "Sea duck with soft down" , "Sea bird" , "Duck with soft feathers" , "Northern sea duck" , "I've noted down" .)