Hotel on quiet upper-class island (6)
I believe the answer is:
honshu
'island' is the definition.
(Honshu is an example)
'hotel on quiet upper-class' is the wordplay.
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'quiet' becomes 'sh'.
'upper-class' becomes 'u' ('u' can be similar in meaning to 'upper-class').
'h'+'on'+'sh'+'u'='HONSHU'
(Other definitions for honshu that I've seen before include "Largest island of mainland Japan" , "Island regarded as the Japanese mainland" , "The main island of Japan" , "part of Japan" , "Largest of the four main islands of Japan" .)