%hoa = ( 'frog-n'      => ['alligator-n'],
         'crocodile-n' => ['alligator-n'],
        );

##</code><code>##

# from the first line: frog-n    about    adage-n    8.8016
for $key (@$hoa{frog-n}){
    $newhash{$key}{about}{adage-n} += 8.8016;
}