To date a Parisian, Italian returns having left at once (5,3)

'to date' is the definition.
(I've seen this in another clue)

'a parisian italian returns having left at once' is the wordplay.
'a parisian' becomes 'un' ('a' in French).
'italian' becomes 'it' (common abbreviation).
'returns' is a reversal indicator.
'having left' becomes 'l' (I am not sure about this - if you are sure you should believe this answer much more).
'at once' becomes 'now' (I've seen this before).
'it' in reverse letter order is 'ti'.
'un'+'ti'+'l'+'now'='UNTIL NOW'

Can you help me to learn more?