Basically, you want a templating system. If you want to keep using the Perl hash syntax, I recommend the following approach:

• Put all your %act hashes into a larger hash, say, %actions
• Use a regular expression to interpolate the hash values:

my %act1 = (
           "food"  => "eat it",
           "drink" => "drink it",
           "Perl"  => "play it");
my %act2 = (
           "food"  => "prepare it",
           "drink" => "be drunk",
           "Perl"  => "write it");
my %actions = (
    act1 => \%act1,
    act2 => \%act2,
);

my %vars = (
    item => \$item,
);

my $out = '-p $act1{$item} -p $act2{$item} -p ... ';
# resp. read that one from a file

# The world's simpled templating system:
$out =~ s-\$(\w+) # the name of the hash (%act1)
          \{      # opening brace
          \$(\w+) # the name of the variable to be used ($item)
          \}      # closing brace
         -
         {
             my $useritem = $vars{ $2 };
             $actions{$1}{$useritem}
         }gxe;
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I haven't tested the code, so likely there are some syntax errors and errors with the specification of the regular expression - I hope that the comments help you enough to fix these.