Computer science can you help me with the last part of the code after mentionedWords.

[perfringo]

So far my code should be correct.

As I have very little knowledge what you want to accomplish I can't say for certain that your statement is incorrect. However, it is safe to say that either split() on line # 16 is redundant or your code does something which you didn't intend.

How your function cleanedup() performs: it eliminates all characters (including non-printing i.e. whitespaces, newlines, CR etc) which are not in alphabet. So result is this:

>>> cleanedup('Monty Python Flying Circus\n')
montypythonflyingcircus                                             # returns one word string
>>> cleanedup('Monty Python Flying Circus\n').split()
['montypythonflyingcircus']                                         # nothing to split on, so one item list
>>> for item in cleanedup('Monty Python Flying Circus\n').split():   
...     print(item)
...
montypythonflyingcircus

Despite the fact that I don't know what your objective is I doubt that this can be called 'correct'. To be more assistive you need to provide more information.