The most common and most likely answer to this crossword clue is the 9 letter word ALGEBRAIC
I've seen this crossword clue in The Times
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Buddy explains!
The straight part
We know that "shown symbolically" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shown symbolically = algebraic.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 ALGEBRAIC mean?
ALGEBRAIC adjective- Of, or relating to, algebra.
- (of an expression, equation or function) Containing only numbers, letters and arithmetic operators.
- (of a number) Which is a root of some polynomial whose coefficients are rational.
- (of a field) Whose every element is a root of some polynomial whose coefficients are rational.
- (of notation) Describing squares by file (referred to in intrinsic order rather than by the piece starting on that file) and rank, both with reference to a fixed point rather than a player-dependent perspective.