The time between day and night (8)
I believe the answer is:
twilight
'the time between day and night' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for twilight that I've seen before include "Gloaming" , "state of decline" , "Illumination at dusk" , "Period of gradual decline or obscurity" , "Partial darkness" .)