Nurse is stirring at break of day (7)
I believe the answer is:
sunrise
'break of day' is the definition.
(synonyms)
'nurse is stirring' is the wordplay.
'stirring' is an anagram indicator.
'nurse'+'is'='nurseis'
'nurseis' is an anagram of 'SUNRISE'.
'at' is the link.
(Other definitions for sunrise that I've seen before include "Daybreak" , "It's preceded by dawn" , "See 21" , "Dawning of the day" , "everyday occurrence in the East" .)