Leave layer covering ancient temple (9)
I believe the answer is:
parthenon
'ancient temple' is the definition.
(ancient Greek temple)
'leave layer covering' is the wordplay.
'leave' becomes 'part' (parting means leaving or separating).
'layer' becomes 'hen' (I've seen this before).
'covering' becomes 'on'.
'part'+'hen'+'on'='PARTHENON'
(Other definitions for parthenon that I've seen before include "Temple of Athene on Acropolis in Athens" , "Temple on the Athenian Acropolis" , "Tourist attraction of Athens" , "ruined Greek temple" , "Ancient temple" .)