The most common and most likely answer to this crossword clue is the 8 letter word ANGSTROM
I've seen this crossword clue in The Guardian
A
N
G
S
T
R
O
M
More clues leading to the result ANGSTROM
- Physicist’s unusually strong backing graduate receives
- Swedish physicist showing uneasiness over computer memory
- Physicist’s worry over traveller
- Worry over radiation initially given to doctor returning to X-ray unit
- Fear Gypsies dropping back a short distance
- Physicist showing anxiety with short memory
- Anxiety around heath, nothing less
- Unit for measuring liquid – not grams
- Tiny gap amongst cracks filled with last of mortar
- Swedish physicist‘s deep uncertainty over computer storage
Buddy explains!
The straight part
We know that "Tiny gap /amongst cracks filled with last of mortar (8)" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tiny gap /amongst cracks filled with last of mortar (8) = angstrom.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 ANGSTROM mean?
ANGSTROM noun- A unit of length equal to 10−10 meters (that is, one ten-billionth of a meter), approximately the size of an atom, and denoted by the symbol Å, used especially to measure the wavelength of electromagnetic radiation or distances between atoms.