Maybe I'm one and don't know it (4)
I believe the answer is:
poet
'maybe i'm one' is the definition.
I can't judge whether this defines the answer.
'don't know it' is the wordplay.
'don't know' becomes 'poe' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'it' becomes ''t' (abbreviation. e.g. in 'tis).
'poe'+'t'='POET'
'and' is the link.
Can you help me to learn more?
(Other definitions for poet that I've seen before include "Tope with a versifier" , "Rhymer" , "'Paul Muldoon or Paula Meehan, say (4)'" , "Maker of verses" , "author" .)