God accordingly defends old temple (8)
I believe the answer is:
pantheon
'temple' is the definition.
(a pantheon is a temple for multiple gods)
'god accordingly defends old' is the wordplay.
'god' becomes 'Pan' (Pan is a Greek god).
'accordingly' becomes 'then' (I've seen this in another clue).
'defends' indicates putting letters inside (inserted letters are defended or protected).
'old' becomes 'o' (abbreviation).
'then' placed around 'o' is 'theon'.
'pan'+'theon'='PANTHEON'
(Other definitions for pantheon that I've seen before include "memorial" , "building that was built to honour gods" , "Circular temple in Rome" , "Temple of all the gods in ancient Greece" , "All the gods of a people or religion" .)