What is the purpose of antanaclasis?
It can be used as a pun and ironic device, or simply as a way of enhancing and contrasting a piece of writing
Antanaclasis is when a word is repeated in a sentence with two or more different meanings for the word. An example of Antanaclasis is in Shakespeares "Much Ado About Nothing," when Beatrice says
"The count is neither sad, nor sick, nor merry, nor
well; but civil count, civil as an orange, and
something of that jealous complexion."
In this passage, the word civil is used twice: The first time it is used in its normal context, but the second time it is used as a pun. Back in Shakespeare's day, the city of Seville was where bitter oranges on, and so the "civil as an orange" is a play of words which say that Claudio is very bitter. Additionally, in Shakespeare's day orange as envy, not green, thus the word "civil" serves two meanings in one.
This is what is meant as an Antanaclasis, a sentence with similar with different meaning. Thus we have civil=polite, and civil=bitter.
I hope I helped!