The most common and most likely answer to this crossword clue is the 10 letter word PREBENDARY
I've seen this crossword clue in The Guardian
P
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Buddy explains!

The straight part
We know that "Canon" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case canon = prebendary.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.
Crossword Answer definitions
PREBENDARY noun- An honorary canon of a cathedral or collegiate church.
- Pertaining to the office or person of a prebendary; prebendal.
- Of or relating to official positions that are profitable for the incumbent, to the allocation of such positions, or to a system in which such allocation is prevalent.