I can offer one additional comment. The /g is unnecessary for your example. (The anchors ^ and $ each refer to a single place in the string.) It may be needed if your real data is a multi-line string, but then you would have other issues to consider.

For your example, you can use:

use strict;
use warnings;
my $row = 'We_need_feed';
my($first_word, $last_word) = $row =~ /^(\w+)_.*_(\w+)$/;
print $first_word, ' ',  $last_word;
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