The most common and most likely answer to this crossword clue is the 11 letter word SOLILOQUISE
I've seen this crossword clue in The Guardian
S
O
L
I
L
O
Q
U
I
S
E
Buddy explains!
The straight part
We know that "Have words with oneself" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case have words with oneself = soliloquise.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SOLILOQUISE mean?
SOLILOQUISE verb- To perform a soliloquy; (of a character) to talk to oneself.