Oracle site (6)
I believe the answer is:
delphi
'oracle site' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for delphi that I've seen before include "Ancient Greek city, site of famous oracle" , "Religious sanctuary of ancient Greece (with an Oracle)" , "'Ancient Greek city, site of the oracle (6)'" , "Temple site on Mt Parnassus" , "'In Greek mythology, the site of the oracle (6)'" .)