Island house: unfinished hut on poles (6)
I believe the answer is:
honshu
'island' is the definition.
(Honshu is an example)
'house unfinished hut on poles' is the wordplay.
'house' becomes 'ho' (abbreviation for house).
'unfinished' means to remove the last letter.
'on' means one lot of letters go next to another.
'poles' becomes 'ns' (North and South poles).
'hut' with its final letter taken away is 'hu'.
'hu' put after 'ns' is 'nshu'.
'ho'+'nshu'='HONSHU'
(Other definitions for honshu that I've seen before include "The largest island unit of Japan" , "The main island of Japan" , "Main Japanese island" , "Largest of the islands forming Japan" , "Largest island of mainland Japan" .)