The most common and most likely answer to this crossword clue is the 7 letter word ALLYING
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More clues leading to the result ALLYING
Buddy explains!

The straight part
We know that "Partnering" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case partnering = allying.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 ALLYING mean?
ALLYING verb- To unite, or form a connection between, as between families by marriage, or between princes and states by treaty, league, or confederacy.
- To connect or form a relation between by similitude, resemblance, friendship, or love.