Immoral behaviour by America? It's a common complaint (9)
I believe the answer is:
sinusitis
'a common complaint' is the definition.
The definition and answer can be both states of affairs as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'immoral behaviour by america? it's' is the wordplay.
'immoral behaviour' becomes 'sin' (sin is immoral).
'by' means one lot of letters go next to another.
'america?' becomes 'U.S.' (United States).
'it's' becomes 'itis' (I can't justify this - if you can you should give a lot more credence to this answer).
'sin'+'us'+'itis'='SINUSITIS'
Can you help me to learn more?
(Other definitions for sinusitis that I've seen before include "Inflammation of nasal cavities" , "Inflammation of head cavities" , "Inflammation in the skull" , "nasal problem" , "Nasal membrane inflammation" .)