Note that fellow criticise US character, a close relative (10)
I believe the answer is:
chimpanzee
'a close relative' is the definition.
The definition and answer can be both animals as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'note that fellow criticise us character' is the wordplay.
'note' becomes 'c' (musical note).
'that fellow' becomes 'him' ('him' refers to a man).
'criticise' becomes 'pan' (informal term meaning to criticise heavily).
'us character' becomes 'zee' (I can't justify this - if you can you should give a lot more credence to this answer).
'c'+'him'+'pan'+'zee'='CHIMPANZEE'
Can you help me to learn more?
(Other definitions for chimpanzee that I've seen before include "African ape with advanced intelligence" , "Great ape" , "Close relative of man" , "MONKEY" , "Intelligent ape" .)