The most common and most likely answer to this crossword clue is the 12 letter word INTERSECTION
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More clues leading to the result INTERSECTION
Buddy explains!

The straight part
We know that "a road junction" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a road junction = intersection.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 INTERSECTION mean?
INTERSECTION noun- The junction of two (or more) paths, streets, highways, or other thoroughfares.
- Any overlap, confluence, or crossover.
- The point or set of points common to two geometrical objects (such as the point where two lines meet or the line where two planes intersect).
- The set containing all the elements that are common to two or more sets.
- The element where two or more straight lines of synchronized skaters pass through each other.http//www.isu.org/vsite/vcontent/content/transnews/0,10869,4844-128590-19728-18885-295370-3787-4771-layout160-129898-news-item,00.html
- The pullback of a corner of monics.