my %hash1 = ( foo => 'bar' );
my %hash2 = ( quz => 'baz' );
$hash1{somekey} = \%hash2;

use Data::Dumper;
print Dumper(\%hash1);
print Dumper( $hash1{somekey}{quz} );
__END__
$VAR1 = {
          'foo' => 'bar',
          'somekey' => {
                         'quz' => 'baz'
                       }
        };
$VAR1 = 'baz';