$_ = "[part1-date] info - [..part2..] [..part3..] part4";
$part = qr /\[(.+?)]/;      # subregex using non-greedy quantifier (slightly easier than /\[([^]]+)\]/)
print "$1 $2 $3" if /$part \w+ - $part $part \w+/;     # prints "part1-date ..part2.. ..part3.."