The most common and most likely answer to this crossword clue is the 7 letter word DIVIDER
I've seen this crossword clue in Financial Times
D
I
V
I
D
E
R
Buddy explains!

The straight part
We know that "Partition" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case partition = divider.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.
What does DIVIDER mean?
DIVIDER noun- An object that separates.
- A device resembling a drawing compass and used to transfer measurements of length.
- The median or central reservation of a highway or other road where traffic in opposite directions are kept separated.
- A person who divides or separates.