Idealist’s article in German covering many sheets of paper (7)
I believe the answer is:
dreamer
'idealist's' is the definition.
(synonyms)
'article in german covering many sheets of paper' is the wordplay.
'article in german' becomes 'der' (I've seen this in another clue).
'covering' indicates putting letters inside.
'many sheets of paper' becomes 'ream' (I can't justify this - if you can you should give a lot more credence to this answer).
'der' placed around 'ream' is 'DREAMER'.
Can you help me to learn more?
(Other definitions for dreamer that I've seen before include "such an unpractical person!" , "One fantasising" , "One lost in abstraction" , "description of an Oxford spire?" , ""You may say I'm a __" (John Lennon)" .)