The Italian stops extremely lovely girl (4)
I believe the answer is:
lily
'girl' is the definition.
(I've seen this before)
'the italian stops extremely lovely' is the wordplay.
'the italian' becomes 'il' (the in Italian).
'stops' means one lot of letters goes inside another.
'extremely' means to remove the middle letters.
'lovely' with its centre taken out is 'ly'.
'il' going into 'ly' is 'LILY'.
(Other definitions for lily that I've seen before include "Flower -- girl" , "Easter flower" , "'Behold the . . . . of the field'" , "Bulb with showy, typically pendulous flowers" , "Fleur-de-lis" .)