Protein one German eats after every starter? (7)
I believe the answer is:
elastin
'protein' is the definition.
(elastin is a kind of protein)
'one german eats after every starter?' is the wordplay.
'one german' becomes 'ein' ('one' in German).
'eats' means one lot of letters goes inside another.
'after every starter?' becomes 'last' (I can't justify this - if you can you should believe this answer much more).
'ein' going around 'last' is 'ELASTIN'.
Can you help me to learn more?
(Another definition for elastin that I've seen is " protein".)