Quits the day before a new start is to be made (4)
I believe the answer is:
even
'quits' is the definition.
(as in 'call it quits')
'day before a new start is to be made' is the wordplay.
I cannot quite see how this works, but
'day' could be 'eve' (eve is a kind of day) and 'eve' is found in the answer.
'new' could be 'n' (common abbreviation eg NT for New Testament) and 'n' is present in the answer.
No letters remain.
This explanation may well be incorrect...
'the' acts as a link.
Can you help me to learn more?
(Other definitions for even that I've seen before include "Yet; level" , "happening to take time off?" , "Smooth, uniform in quality" , "end of the day, reading poetry" , "Stable" .)