The most common and most likely answer to this crossword clue is the 9 letter word SELECTING
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Buddy explains!

The straight part
We know that "Favouring" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case favouring = selecting.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 SELECTING mean?
SELECTING verb- To choose one or more elements of a set, especially a set of options.
- To obtain a set of data from a database using a query.