You can't split it up completely,

Just a tiny bit more, mixing your "solution" with lidden's:

sub compare {
    my @A = split /:/, $a;
    my @B = split /:/, $b;
    $A[0] <=> $B[0];
}

my @sorted = sort compare @table;
print @sorted;
[download]

(Incidentally I also changed the first argument to split, since it must be a pattern - strings are automatically converted of course, but there's one special case, so...)

If it ain't clear like this... I don't know what could ever be!!