A general use USB cable should work. Note that some USB cables are power only; of course, that wouldn’t work with the Clip to transmit data. Also, the quality of USB cables varies; I have a couple of retractable USB cables (from Hong Kong) that only transmit power and will not do data, even though they are not sold as having any limitation. I would recommend that you try another, dependable-brand cable.
The Clip+ needs 5 V. (no more–that will blow it out) and around 500 mAmp or more (a bit less is fine, and simply may recharge the Clip slower–to around 350 mA or so has been found OK). This ia a pretty common standard–you already may have a USB charger around that will work. For example, some Motorola cellphone chargers (such as for the Razr) will work, as well as some Mio GPS chargers. Also, Wal-Mart sells chargers that will work with the Clip players, and chargers found to be fine with the Clip players also are made by DLO (the PowerBug), Macally, FiiO (it makes a nifty 3-in-1 charger: AC power supply, battery charger, and portable battery pack), Belkin and others; even if the chargers don’t say they are made for the Clip players (few do), they can be just fine, including chargers that say they work for Sansa SlotRadio players and the Fuze (while USB cables that sometimes come with those chargers may not work with the Clip players’ standard connection, the charger itself will be just fine).
Hope this helps–