use warnings;
use strict;
use feature 'refaliasing';
use Data::Dump;
use Tie::Subset::Hash;

my %hash;
@hash{"a".."e"} = 41..45;

dd \%hash;

tie my %hash2, 'Tie::Subset::Hash', \%hash, ['b'];
\%hash = \%hash2;

dd \%hash;

__END__

Aliasing via reference is experimental at foo.pl line 13.
{ a => 41, b => 42, c => 43, d => 44, e => 45 }
{
  # tied Tie::Subset::Hash
  b => 42,
}