Particle in some science (7)
I believe the answer is:
anatomy
'science' is the definition.
(anatomy is a kind of science)
'particle in some' is the wordplay.
'particle' becomes 'atom' (synonyms).
'in' is an insertion indicator.
'some' becomes 'any' (similar in meaning).
'atom' going into 'any' is 'ANATOMY'.
(Other definitions for anatomy that I've seen before include "Bodily structure of animal or plant" , "Scientific study of bodily structure" , "Study of animal structures" , "Examining body" , "Study of (physical structure of) living things" .)