The most common and most likely answer to this crossword clue is the 8 letter word PYRAMIDS
I've seen this crossword clue in The Guardian
P
Y
R
A
M
I
D
S
More clues leading to the result PYRAMIDS
- Woodpiles making energy amid tombs
- Without a second thought, I’d followed girl back to the ancient tombs
- PM’s diary sets out high points of NE African tour
- PM’s diary set out high points of Egyptian tour
- Quiet girl offered up passes for monuments
- In past, oddly find princess and queen climbing ancient structures
Buddy explains!

The straight part
We know that "the ancient tombs" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the ancient tombs = pyramids.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 PYRAMIDS mean?
PYRAMIDS noun- An ancient massive construction with a square or rectangular base and four triangular sides meeting in an apex, such as those built as tombs in Egypt or as bases for temples in Mesoamerica.
- A construction in the shape of a pyramid, usually with a square or rectangular base.
- A solid with triangular lateral faces and a polygonal (often square or rectangular) base.
- A medullary pyramid, the medial-most bumps on the ventral side of the medulla oblongata
- The game of pool in which the balls are placed in the form of a triangle at spot.
- A pyramid scheme.
- Alternative letter-case form of Pyramid. (a solitaire card game)
- The triangular layout of cards in the game of Pyramid.
- An approximately triangular headline consisting of several centered lines of text of increasing length.
- To build up or be arranged in the form of a pyramid.
- To combine (a series of genes) into a single genotype.
- To employ, or take part in, a pyramid scheme.
- To engage in pyramid trading.
- The game of pyramid pool.