Ordered with full particulars (8)
I believe the answer is:
detailed
'ordered with full particulars' is the definition.
The definition and answer can be both related to thinking as well as being past participle verbs.
Perhaps they are linked in a way I don't understand?
This is the entire clue.
Can you help me to learn more?
(Other definitions for detailed that I've seen before include "Giving full particulars" , "Minutely described" , "Itemized or intricate" , "Comprehensive" , "Elaborate" .)