(Reuters) -The U.S. Federal Reserve needs to maintain a restrictive stance of monetary policy to get inflation down to its 2% target, Cleveland Fed President Beth Hammack told CNBC's Squawk Box Europe on Monday. "It's a challenging time for monetary policy. We are being challenged on both sides of our mandate," she said, referring to inflation and maximum employment. "When I balance those two sides of our mandate, I think we really need to maintain a restrictive stance of policy so that we can get infl ...