Figure study (5)
I believe the answer is:
maths
This could be a double definition.
'figure' is the first definition.
The definition and answer can be both related to thinking as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'study' is the second definition.
(maths is a kind of study)
Can you help me to learn more?
(Other definitions for maths that I've seen before include "Subject involving figures (abbr)" , "The science of number, quantity and space" , "A school subject (abbr.)" , "Algebra, geometry, calculus etc (abbr)" , "18 across subject" .)