Ballet dancer beginning to dance with a poor nurse (7)
I believe the answer is:
danseur
'ballet dancer' is the definition.
(I know that danseur is a type of ballet dancer)
'beginning to dance with a poor nurse' is the wordplay.
'beginning to' indicates taking the first letters.
'with' indicates putting letters inside.
'poor' is an anagram indicator.
The initial letter of 'dance' is 'd'.
'nurse' with letters rearranged gives 'nseur'.
'a' going inside 'nseur' is 'anseur'.
'd'+'anseur'='DANSEUR'
(Other definitions for danseur that I've seen before include "Entertainer" , "Male ballet performer" , "Participant in The Rite of Spring perhaps" , "Male ballet dancer, partner of a ballerina" , "Ballerina's partner" .)