Attraction of evening swapping partners (5)
I believe the answer is:
sight
'attraction' is the definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Maybe there's an association between them I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for sight that I've seen before include "A lot" , "Looking" , "Notice" , "Glimpse" , "Spectacle; aiming aid" .)