A big fan of Nathaniel is articulate (8)
I believe the answer is:
intonate
'articulate' is the definition.
The definition and answer can be both to do with communicating as well as being verbs in their base form.
Maybe there's an association between them I don't understand?
'a big fan of nathaniel' is the wordplay.
'a big fan of' becomes 'into' (I've seen this in another clue).
'nathaniel' becomes 'nate' (I can't justify this - if you can you should believe this answer much more).
'into'+'nate'='INTONATE'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for intonate that I've seen before include "chant solemnly" , "say" .)