Mistress of curate's no different (9)
I believe the answer is:
courtesan
'mistress' is the definition.
(I know that courtesan is a type of mistress)
'of curate's no different' is the wordplay.
'of' becomes 'o''.
'no' becomes 'n' (common abbreviation).
'different' indicates an anagram (letters placed in a different order).
'o'+'curates'+'n'='ocuratesn'
'ocuratesn' with letters rearranged gives 'COURTESAN'.
(Other definitions for courtesan that I've seen before include "loose woman" , "Fanny Hill, perhaps" , "Kept woman" , "High-class prostitute" , "odalisque" .)