The most common and most likely answer to this crossword clue is the 15 letter word UNPARLIAMENTARY
I've seen this crossword clue in Independent
U
N
P
A
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A
M
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More clues leading to the result UNPARLIAMENTARY
Buddy explains!
The straight part
We know that "a minister shouldn’t be" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a minister shouldn’t be = unparliamentary.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 UNPARLIAMENTARY mean?
UNPARLIAMENTARY adjective- Unsuitable to be used in parliament
- Contrary to the rules of parliament