"The man asks for wine."
Translation:L'homme demande du vin.
1) in French "demander" is directly transitive (no preposition, neither "pour" nor any other)
2) this sentence is a statement, not an imperative. The format of your sentence, with "demande" upfront, is that of an order.
Back translating your proposed sentence would give: "Request the man for the wine!"
"ask the man for the wine" is in imperative and would translate to "demande(z) du vin à l'homme".
"demander quelque chose à quelqu'un": the thing asked for is always a direct object in French (no preposition, no "pour", nothing).
"l'homme demande du vin à la femme" is the simpler way to say it. Now, if the wine were qualified, you could reverse the order between the direct and the indirect objects:
- l'homme demande à la femme du vin de sa cave = the man asks the woman for wine from his cellar
Not all verbs are used the same way; some need a preposition before their object, others don't.
Please compare: "the man asks for something" vs "the man requests something".
"To ask for" needs the preposition "for", but "to request" does not, and the French verb "demander" not either.
- The man asks for wine = L'homme demande du vin.
Besides, "demander" can have an indirect object, usually the person or organization something is asked to/from.
- The man asks the server for wine/The man asks for wine from the server = L'homme demande du vin au (à+le) serveur