my %subckt;
my $name;
my $want;

while (<DATA>) {
    if (my $ff = /\.subckt\s+(\w+)/ .. /\.ends/) {
        $name = $1 if $ff == 1;
        $subckt{$name} .= $_;
    } else {
        $want = $1 if /^\s*xa1\b.*\b(\w+)\s*$/;
    }
}

print $subckt{$want};