Letter from an oddball (9)
I believe the answer is:
character
I believe this clue is a double definition.
'letter' is the first definition.
(written character)
'an oddball' is the second definition.
(thesaurus)
'from' acts as a link.
(Other definitions for character that I've seen before include "Letter or number" , "eccentric individual" , "Someone in play" , "Distinctive nature" , "card" .)