No simple mental condition (7)
I believe the answer is:
complex
This might be a double definition.
'no' is the first definition.
The definition and answer can be both substances as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'simple mental condition' is the second definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Maybe they are linked in a way I don't understand?
Can you help me to learn more?
(Other definitions for complex that I've seen before include "Convoluted" , "Not simple, say a group of feelings" , "Hard to understand or of many parts" , "Obsession - not simple" , "psychological state" .)