Translation:A wallet is a container for carrying money.
PIV defines "hundujo" as "Dometo, en kiu oni tenas gardohundon dumtage" (small house, in which one keeps a guard dog during the day) -- I would call it a kennel (UK) / doghouse (US).
But it could theoretically apply also to a carrying container for a dog, or even a cage.
Interestingly there seems to be a bit of disagreement between my various dictionaries on this point. Aside from monujo I'm also finding words like burso (pouch tied to belt), retikulo (handbag) and ŝultrosako (shoulderbag) as well as biletujo and monbilujo (both being specifically "wallet") as well as several others in books and files which I just didn't leave open on my desk. I notice that nothing claimed to mean "money clip."
I think that perhaps we can accept that monujo is a generic term for a place where we keep money, and if we need to be more exact then we can delve into our various dictionaries, or whatever, and choose from the various terms available there.
And I have noticed that Duo will go with the generic whenever possible.
If this was a choose-the-right-answer dropdown for the first word, then your answer is incorrect, because "ujo por porti monon" is singular, so "monujo" should be as well.
If the rest had been "ujoj por porti monon", then "monujoj" would have been appropriate.
i.e. either "A wallet is a container..." or "Wallets are containers...".
You essentially picked "Wallets is a container for carrying money".
Nu, Mi supozas, ke: "for carry money" ŝajnus prave se, kiel vi diris, vi ne parolas bone la anglan. Sed, kiel denaska anglolingvano mi devas diri, ke ĝi malpravas.
La frazo estas en la nuna tenso ĉar ekzistas la vorton estas (is) kaj ĉiuj kiuj sekvas devas esti rigardata, ankaŭ, en la virtuala nuna tenso. Do, la prava frazeto devas esti "For carrying money."
Mi esperas, ke tiu ĉi helpos vin.