Were wrong about Spithead being in Germany! (5)

I believe the answer is:
weser
'in germany' is the definition.
The definition suggests a singular noun which matches the answer.
'were wrong about spithead' is the wordplay.
'wrong' indicates anagramming the letters.
'about' is an insertion indicator.
'spithead' becomes 's' (head letter of 'spit').
'were' is an anagram of 'weer'.
'weer' placed around 's' is 'WESER'.
'being' acts as a link.
Can you help me to learn more?
(Other definitions for weser that I've seen before include "German runner" , "Er, sew up the German river" .)
