The most common and most likely answer to this crossword clue is the 10 letter word ACHROMATIC
I've seen this crossword clue in The Guardian
A
C
H
R
O
M
A
T
I
C
More clues leading to the result ACHROMATIC
- Colourless chief scented bottles
- A church intimate with no name, lacking colour
- Act with choir performing about half of Maya lacking colour
- Colourless church with scent outside
- Old telly model’s leads; archaic set without colour
- A dreamer with no name embraces church, having no shade
- Without colour, it's pain almost, sentimental without a point
- Colourless like benzene, which contains carbon and hydrogen
Buddy explains!

The straight part
We know that "without colour/without colour" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case without colour/without colour = achromatic.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 ACHROMATIC mean?
ACHROMATIC adjective- Free from color; transmitting light without color-related distortion.
- Containing components such as achromatic lenses and prisms, designed to prevent color-related distortion.
- Uncolored; not absorbing color from a fluid; -- said of tissue
- Having only the diatonic notes of the scale; not modified by accidentals.
- Being achromatic in subject