Geological field failed conic test (9)
I believe the answer is:
tectonics
'geological field' is the definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Maybe there's a link between them I don't understand?
'failed conic test' is the wordplay.
'failed' indicates an anagram.
'conic'+'test'='conictest'
'conictest' is an anagram of 'TECTONICS'.
Can you help me to learn more?
(Other definitions for tectonics that I've seen before include "scientific study of buildings" , "Moving plates" , "Structural geology" , "Processes in the earth's crust" .)