Untidy woman's a hospital attendant (10)
I believe the answer is:
disorderly
'untidy' is the definition.
('disorderly' can be similar in meaning to 'untidy')
'woman's a hospital attendant' is the wordplay.
'woman's' becomes 'dis' (Di is short for Diana).
'a hospital attendant' becomes 'orderly' ('orderly' can be a synonym of 'hospital attendant').
'dis'+'orderly'='DISORDERLY'
(Other definitions for disorderly that I've seen before include "Lacking organisation" , "Unruly" , "disturbance of the peace" , "Companion of drunk" , "undisciplined" .)