In view of the fact that one's a spectator (6)
I believe the answer is:
seeing
'the fact that one's a spectator' is the definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'in view' is the wordplay.
I cannot quite understand how this works, but
'in' is found in the answer.
'view' could be 'see' (synonyms) and 'see' is found within the answer.
A single letter 'g' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for seeing that I've seen before include "Observing - understanding" , "... is believing, it's said" , "Watching" , "Viewing" , "Perceiving by eye" .)