Mattarella for one in restaurant (7)
I believe the answer is:
italian
'restaurant' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'mattarella for one' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'an' (an apple is one apple) and 'an' is located in the answer.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for italian that I've seen before include "drink" , "Dante's tongue" , "Eg, Native of Turin" , "Nationality of citizen of Capri" , "From Bologna?" .)