The most common and most likely answer to this crossword clue is the 7 letter word TESSERA
I've seen this crossword clue in Financial Times
T
E
S
S
E
R
A
More clues leading to the result TESSERA
- Password as reset works
- Token date that’s important close to girl
- Piece of mosaic put back before start of study period
- Tile God put back
- Greek god positioned the other way in part of mosaic
- Literary heroine having time for piece of mosaic work
- Die long time after the Hardy girl
- Queen interrupting property being returned — a classical piece of marble?
- Small piece of mosaic being inserted into mobile art
- Ancient god put back in piece of mosaic
Buddy explains!

The straight part
We know that "Die" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case die = tessera.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 TESSERA mean?
TESSERA noun- A small square piece of stone, wood, ivory or glass used for making a mosaic.
- Complex-ridged surface feature seen on plateau highlands of Venus and perhaps on Triton