Of French and German and English county (5)
I believe the answer is:
devon
'english county' is the definition.
(Devon is an English county)
'of french and german' is the wordplay.
'of french' becomes 'de' ('of' in French).
'and' is a charade indicator (letters next to each other).
'german' becomes 'von' (common element in German surnames).
'de'+'von'='DEVON'
'and' acts as a link.
(Other definitions for devon that I've seen before include "Ilfracombe's county" , "County in SW England" , "Clotted-cream county" , "part of England?" , "English county" .)