Quits the day before exhausted nurses (5)
I believe the answer is:
evens
'quits' is the definition.
(as in 'call it quits')
'day before exhausted nurses' is the wordplay.
'day' becomes 'eve' (eve is a kind of day).
'before' says to put letters next to each other.
'exhausted' means to remove the middle letters (the word is emptied out or exhausted).
'nurses' with its middle taken out is 'ns'.
'eve'+'ns'='EVENS'
'the' is the link.
(Other definitions for evens that I've seen before include "Kind of betting odds on seven" , "Makes equal" , "Exchange, substitute" , "Presses" , "Likelihood" .)