Was it split in great ominousness? (4)
I believe the answer is:
atom
'was it split' is the definition.
I can't judge whether this defines the answer.
'in great ominousness?' is the wordplay.
'in' indicates a hidden word.
'ATOM' is hidden in the letters of 'great ominousness'.
Can you help me to learn more?
(Other definitions for atom that I've seen before include "Smallest particle in an element able to take part in a chemical reaction" , "Small particle of matter" , "The tiniest particle" , "Particle; molecule" , "An explosive particle as in bomb" .)