Expresses disapproval as short novel contains embarrassing error (6)
I believe the answer is:
booboo
'embarrassing error' is the definition.
'booboo' can be an answer for 'error' (I've seen this before). I'm unsure of the 'embarrassing' bit.
'expresses disapproval as short novel' is the wordplay.
'expresses disapproval as' becomes 'boo' (I can't explain this - if you can you should believe this answer much more).
'short' means to remove the last letter.
'novel' becomes 'book'.
'book' with its final letter taken away is 'boo'.
'boo'+'boo'='BOOBOO'
'contains' acts as a link.
Can you help me to learn more?
(Other definitions for booboo that I've seen before include "Having got animated, bear" , "mistake" , "Blunder" , "Error" .)