Sicilian criminal’s girl in old Chinese leader’s circle (7)
I believe the answer is:
mafioso
'sicilian criminal's' is the definition.
(I've seen this before)
'girl in old chinese leader's circle' is the wordplay.
'girl' becomes 'fi' (nickname for Fiona).
'in' means one lot of letters goes inside another.
'old chinese leader's' becomes 'Mao's' (Chairman Mao).
'circle' becomes 'O' (O is a circle).
'fi' placed within 'maos' is 'mafios'.
'mafios'+'o'='MAFIOSO'
(Other definitions for mafioso that I've seen before include "One of the mob" , "Italian gangster" , "Family man" , "Sicilian gangster" , "Member of a Sicilian mob" .)