The most common and most likely answer to this crossword clue is the 9 letter word EXCLUSION
I've seen this crossword clue in The Times
E
X
C
L
U
S
I
O
N
More clues leading to the result EXCLUSION
Buddy explains!
The straight part
We know that "Prohibition" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case prohibition = exclusion.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 EXCLUSION mean?
EXCLUSION noun- The act of excluding or shutting out; removal from consideration or taking part.
- The act of pushing or forcing something out.
- An item not covered by an insurance policy.