Theatrical group (4)
I believe the answer is:
camp
This clue might be a double definition.
'theatrical' is the first definition.
(I've seen this before)
'group' is the second definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Maybe you can see a link between them that I can't see?
Can you help me to learn more?
(Other definitions for camp that I've seen before include "Distance down" , "David, for instance" , "Affected; base for troops" , "Military settlement" , "Affected - group of tents" .)