Learn Italian: Il commensale desidera che Marco porti un altro stuzzichino. - The dinner guest wants Marco to bring another snack.

You can use quello che or ciò che to create a pseudo-cleft sentence. The sentence becomes: Quello che il commensale desidera è che Marco porti un altro stuzzichino. This structure highlights the specific desire, functioning exactly like the English structure: What the dinner guest wants is...

Why do we use porti instead of the indicative porta?

The main verb desiderare expresses a wish or desire. When a sentence expresses a wish, emotion, or doubt using che, and the subjects of the two clauses are different (il commensale vs. Marco), Italian requires the subjunctive mood. Porti is the present subjunctive of portare.

Is there a difference between commensale and ospite?

Yes. Ospite is a versatile word that can mean either guest or host in almost any context. Commensale specifically shares a root with mensa (table) and refers strictly to someone sharing a meal with others at the same table.

Why doesn't un altro have an apostrophe here?