Latin sweetheart upset without classy charm (7)
I believe the answer is:
enamour
'charm' is the definition.
(I know that charm can be written as enamour)
'latin sweetheart upset without classy' is the wordplay.
'latin' becomes 'roman' (I've seen this before).
'sweetheart' becomes 'e' (the heart/centre of 'sweet').
'upset' says the letters should be written in reverse.
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'classy' becomes 'u' (I've seen this in other clues).
'roman'+'e'='romane'
'romane' back-to-front is 'enamor'.
'enamor' going around 'u' is 'ENAMOUR'.
(Other definitions for enamour that I've seen before include "sweep one off one's feet" , "Delight" , "Inspire with love; charm" , "entrance" , "Our name (anag)" .)