Criticise the combination of old and new in temple (8)
I believe the answer is:
pantheon
'temple' is the definition.
(pantheon is a kind of temple)
'criticise the combination of old and new' is the wordplay.
'criticise' becomes 'pan' (informal term meaning to criticise heavily).
'combination of' indicates anagramming the letters (I've seen this in other clues).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'and' says to put letters next to each other (I've seen this in other clues).
'new' becomes 'n'.
'o' after 'n' is 'no'.
'no' with letters rearranged gives 'on'.
'pan'+'the'+'on'='PANTHEON'
'in' acts as a link.
(Other definitions for pantheon that I've seen before include "church" , "list of great names" , "Temple of all the gods in ancient Greece" , "Circular temple in Rome" , "Temple dedicated to all the gods" .)