Naive boy touring North Island (9)
I believe the answer is:
greenland
'island' is the definition.
(I know that Greenland is a island)
'naive boy touring north' is the wordplay.
'naive' becomes 'green' (similar in meaning).
'boy' becomes 'lad' (informal term for boy).
'touring' indicates putting letters inside (touring can mean going round).
'north' becomes 'N' (abbreviation).
'lad' enclosing 'n' is 'land'.
'green'+'land'='GREENLAND'
(Other definitions for greenland that I've seen before include "Island with local name Kalaallit Nunaat" , "Englander in island owned by Denmark" , "5 island north of 13" , "Island mostly north of the Arctic circle" , "icy mountain here?" .)