American Financial Unit Receives Subpoena  NEW YORK (Reuters) - American Financial Group Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=AFG.N target=/stocks/quickinfo/fullquote"&gt;AFG.N&lt;/A&gt;  said on Monday its property and casualty insurance unit  received a subpoena from New York Attorney General Eliot  Spitzer's office concerning legal malpractice insurance.