The most common and most likely answer to this crossword clue is the 9 letter word COALITION
I've seen this crossword clue in The Guardian
C
O
A
L
I
T
I
O
N
More clues leading to the result COALITION
- League has location for playing across island
- State introduces a Liberal to replace New Democrat form of government
- Fusion fuel has appeal over charged particle
- Merger company landed with current working
- Multiple parties? Firm came down on holding one
- Tory involving a Liberal with it, I observe at the outset?
- Independent standing in location upset governing arrangement …
- Alliance of nearly everybody in Congress
- Temporary alliance getting into trouble after Conservative leader starts to oppose all liberal initiatives
- Governmental arrangement – trick taking in a lot, I repeatedly suspect
Buddy explains!

The straight part
We know that "Partnership" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case partnership = coalition.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 COALITION mean?
COALITION noun- A temporary group or union of organizations, usually formed for a particular advantage.
- The collective noun for a group of cheetahs.