The most common and most likely answer to this crossword clue is the 8 letter word GLEAMING
I've seen this crossword clue in The Guardian
G
L
E
A
M
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Buddy explains!
The straight part
We know that "flashy / flashy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case flashy / flashy = gleaming.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 GLEAMING mean?
GLEAMING verb- To shine; to glitter; to glisten.
- To be briefly but strongly apparent.
- To disgorge filth, as a hawk.
- A flash of reflected light.
- Having a bright sheen.