The old man with a girl, a dish (6)
I believe the answer is:
paella
'a dish' is the definition.
(paella is a kind of dish)
'the old man with a girl' is the wordplay.
'the old man' becomes 'pa' ('pa' can be a synonym of 'old man').
'with' says to put letters next to each other.
'a girl' becomes 'ella' (**).
'pa'+'ella'='PAELLA'
(Other definitions for paella that I've seen before include "something to eat" , "Traditional Spanish dish" , "Spanish dish of rice, shellfish, etc" , "Meal" , "Spanish dish of rice, saffron etc." .)