Nurse is knocked back, having to go without a date (4,3)
I believe the answer is:
sine die
'without a date' is the definition.
(Latin term meaning without a set date)
'nurse is knocked back having to go' is the wordplay.
'nurse' becomes 'EN' (abbreviation for state-enrolled nurse).
'knocked back' says the letters should be written in reverse.
'having' says to put letters next to each other.
'to go' becomes 'die' ('die' can be a synonym of 'go').
'en'+'is'='enis'
'enis' written backwards gives 'sine'.
'sine'+'die'='SINE DIE'
(Other definitions for sine die that I've seen before include "With no date agreed" , "With no date set for resumption (Latin)" , "With no appointed date for resumption (Latin)" , "undated" , "Indefinitely (Latin, as applied to sporting suspensions)" .)