Horseman skipping initial horse trial (9)
I believe the answer is:
nightmare
'trial' is the definition.
The definition and answer can be both related to thinking as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'horseman skipping initial horse' is the wordplay.
I cannot quite understand how this works, but
'horse' could be 'mare' (mare is a kind of horse) and 'mare' is present in the answer.
The remaining letters 'night' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for nightmare that I've seen before include "that might upset the rest" , "fiend" , "Horrifying dream" , "Horrifying experience" , "Frightening dream" .)