Dusk found last character, single, in mysterious place (8,4)
I believe the answer is:
twilight zone
'mysterious place' is the definition.
The definition suggests a singular noun which matches the answer.
'dusk found last character single' is the wordplay.
'dusk' becomes 'twilight' (synonyms).
'found' says to put letters next to each other.
'last character' becomes 'Z'.
'single' becomes 'one' (a single thing - only one).
'twilight'+'z'+'one'='TWILIGHT ZONE'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for twilight zone that I've seen before include "Ambiguous area" , "Area of urban decay" , "Derelict area" , "Transitional state" , "Grey area" .)