You are clearing the hash and not the array also.

use warnings;
use strict;
use Data::Dumper;

my $string = "column08=Submit & column10=Delivered & column09=Somethin
+g";
my @matches = grep defined, split / ([|&]) /, $string;
my %hash = ();
my @return_array = ();
my @symbol_array = (); # dead code
foreach my $one (@matches)
{
    if (($one =~ tr/=//) == 1)
    {
        my ($key,$value)=(split /=/,$one);
                %hash = ();
                @return_array = (); # clear the array also
        $hash{'term'}{$key} = $value;
        push (@return_array,%hash);
    }
    else # dead code
    {
        push (@symbol_array,$one);
    }

}
print Dumper \%hash;
print Dumper \@return_array;
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