Nurse, they say, requires groups of nine? (7)
I believe the answer is:
enneads
'groups of nine?' is the definition.
(I've seen this in another clue)
'nurse they say' is the wordplay.
I cannot quite see how this works, but
'nurse' could be 'en' (abbreviation for enrolled nurse) and 'en' is found in the answer.
This explanation may well be incorrect...
'requires' acts as a link.
Can you help me to learn more?
(Other definitions for enneads that I've seen before include "groups of nine" , "Eights plus coxes, perhaps" , "Groups with members one over the eight" , "Groups appearing one over the eight" , "Sane end (anag.)" .)