Wayward Sumerian daughter's nanny (9)
I believe the answer is:
nursemaid
'nanny' is the definition.
(both can mean someone who looks after children)
'wayward sumerian daughter's' is the wordplay.
'wayward' indicates anagramming the letters (wayward means out of control or chaotic).
'daughter' becomes 'd' (genealogical abbreviation).
'sumerian' is an anagram of 'nursemai'.
'nursemai'+'d'='NURSEMAID'
(Other definitions for nursemaid that I've seen before include "child minder" , "caretaker" , "Nanny" , "Woman tending a child or children" , "She may attend to babe" .)