Possibly unseat Jane (6)
I believe the answer is:
austen
'jane' is the definition.
(I know that jane can be written as Austen)
'possibly unseat' is the wordplay.
'possibly' indicates anagramming the letters.
'unseat' anagrammed gives 'AUSTEN'.
(Other definitions for austen that I've seen before include "Persuasion author" , "Mansfield Park author" , "Future woman of note" , "Jane - - (lit.)" , "Jane ......wrote Sense and Sensibility" .)