The ArrayRef accessor returns an arrayref which you can use like any other arrayref . . .

package Spoo;
use Moose;

has 'a' => ( is => 'rw', isa => 'ArrayRef', default => sub { [] }, );

no Moose;

package main;

my $s = Spoo->new;

push @{ $s->a }, qw( a b c );

my $idx = 0;
for my $x ( @{ $s->a } ) {
  print $idx++, ": $x\n";
}

exit 0;

__END__
[download]