Temple in Japan, the one that's hidden (8)
I believe the answer is:
pantheon
'temple' is the definition.
(pantheon is a kind of temple)
'japan the one that's hidden' is the wordplay.
'that's hidden' indicates a hidden word.
'PANTHEON' is hidden in the letters of 'japan the one'.
'in' is the link.
(Other definitions for pantheon that I've seen before include "building that was built to honour gods" , "Hall of fame" , "Temple dedicated to all the gods" , "Temple of all the gods in ancient Greece" , "All the gods of a people or religion" .)