That works as expected

#              0     1     2     3     4     5     6     7
my @array = qw(part1 part2 part3 part4 part5 part6 part7 part8);
print splice(@array, 5, 1), $/;
print @array;

__output__

part6
part1part2part3part4part5part7part8
[download]

As the docs for splice say, it Removes the elements designated by OFFSET and LENGTH from an array, and replaces them with the elements of LIST, if any.
HTH

_________
broquaint