China may be thus, or Tonga’s islands? (8)
I believe the answer is:
friendly
I believe this is a double definition.
'china may be thus' is the first definition.
(china [plate] is Cockney rhyming slang for 'mate')
'tonga's islands?' is the second definition.
(Tonga has been known as the Friendly Islands)
'or' acts as a link.
(Other definitions for friendly that I've seen before include "Amicable and kindly" , "prepared to talk to fellow passengers?" , "on the same side" , "match?" , "Well-disposed" .)