Crossword Genius

Fantastic mosaic - but very small (9)

Ross

I believe the answer is:

subatomic

'very small' is the definition.

'fantastic mosaic but' is the wordplay.
'fantastic' indicates anagramming the letters.
'mosaic'+'but'='mosaicbut'
'mosaicbut' anagrammed gives 'SUBATOMIC'.

(Other definitions for subatomic that I've seen before include "Of smaller than elementary particles" , "Like 9 across" , "Smaller than a basic particle of matter" .)

I've seen this clue in The Independent.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.