A native of Rouen, maybe, and not an island (6)
I believe the answer is:
norman
'a native of rouen maybe' is the definition.
(Rouen is part of Normandy)
'and not an island' is the wordplay.
'and not' becomes 'nor' ('nor' means 'and also not').
'an island' becomes 'Man' (the Isle of Man is an example).
'nor'+'man'='NORMAN'
(Other definitions for norman that I've seen before include "- Mailer, US author" , "British comedian, once a cult figure in Albania, d. 2010" , "Someone who's not British" , "12th century invasion of Ireland" , "15 [JANE] the clothing company" .)