sub some_sub {
  my $var;
  my $nested_sub = sub {
    .
    .
    if ($var eq q/value/) {
      # Do something
    } else {
      # Do something else
      $var = q/some_other_val/;
    }
  };

  # Do some stuff
  $var = q/value/;
  &$nested_sub(args);
  if ($val eq q/some_other_val/) {
    # Do some more stuff
  } else {
    # Do something else entirely
  }
  .
}