The most common and most likely answer to this crossword clue is the 10 letter word CONGRUENCE
I've seen this crossword clue in The Guardian
C
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Buddy explains!
The straight part
We know that "match" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case match = congruence.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 CONGRUENCE mean?
CONGRUENCE noun- The quality of agreeing or corresponding; being suitable and appropriate.
- A relation between two numbers indicating they give the same remainder when divided by some given number.
- The quality of being isometric — roughly, the same measure and shape.
- More generally: any equivalence relation defined on an algebraic structure which is preserved by operations defined by the structure.