What you are looking at needs swapping of date and time with determination (4)
I believe the answer is:
grit
'determination' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for grit that I've seen before include "Small particles of stone or sand" , "Grains of rock or sand" , "Kind of courage or dirt" , "Toughness" , "Persevering courage" .)