The most common and most likely answer to this crossword clue is the 6 letter word DELPHI
I've seen this crossword clue in The Daily Telegraph
D
E
L
P
H
I
More clues leading to the result DELPHI
- Indian city accommodates parking for historic location
- Key Greek character where Greeks lived
- Ancient sanctuary, peaceful initially in new capital city
- Oracle’s place, quiet in Asian metropolis
- Indian city contains quiet sanctuary
- Prince entering capital city of ancient Greece
- Parking in Indian city, historic city
- Oracle’s source, or prophet’s, in city
- Old programming language used in place of Oracle
- Old city I’d help to rebuild
Buddy explains!

The straight part
We know that "place of oracle" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case place of oracle = delphi.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.