Cryptic crossword clue
Three-D art, perhaps, last seen in Giza – The Pyramids 10

The most common and most likely answer to this crossword clue is the 10 letter word TETRAHEDRA

I've seen this crossword clue in Financial Times
T
E
T
R
A
H
E
D
R
A

Buddy explains!

The straight part
We know that "The Pyramids" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the pyramids = tetrahedra.
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 TETRAHEDRA mean?

TETRAHEDRA noun
  1. A polyhedron with four faces; the regular tetrahedron, the faces of which are equal equilateral triangles, is one of the Platonic solids.

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