The most common and most likely answer to this crossword clue is the 13 letter word CRYSTAL-CLEAR
I've seen this crossword clue in The Times
C
R
Y
S
T
A
L
-
C
L
E
A
R
Buddy explains!
The straight part
We know that "with absolute lucidity" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case with absolute lucidity = crystal-clear.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 CRYSTAL-CLEAR mean?
CRYSTAL-CLEAR adjective- Completely clear and understood.
- Visually clear, a sharp image, high acuity.