The most common and most likely answer to this crossword clue is the 11 letter word PROPOSITION
I've seen this crossword clue in The Sunday Telegraph
P
R
O
P
O
S
I
T
I
O
N
More clues leading to the result PROPOSITION
Buddy explains!
The straight part
We know that "Plan" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case plan = proposition.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 PROPOSITION mean?
PROPOSITION noun- The act of offering (an idea) for consideration.
- An idea or a plan offered.
- (business settings) The terms of a transaction offered.
- In some states, a proposed statute or constitutional amendment to be voted on by the electorate.
- (grammar) A complete sentence.
- The content of an assertion that may be taken as being true or false and is considered abstractly without reference to the linguistic sentence that constitutes the assertion; (Aristotelian logic) a predicate of a subject that is denied or affirmed and connected by a copula.
- An assertion so formulated that it can be considered true or false.
- An assertion which is provably true, but not important enough to be called a theorem.
- A statement of religious doctrine; an article of faith; creed.
- The part of a poem in which the author states the subject or matter of it.
- To make a suggestion of sexual intercourse to (someone with whom one is not sexually involved).
- To make an offer or suggestion to (someone).