The most common and most likely answer to this crossword clue is the 10 letter word EXTRAMURAL
I've seen this crossword clue in Financial Times
E
X
T
R
A
M
U
R
A
L
More clues leading to the result EXTRAMURAL
- Old transport on river beyond the walls
- Run artist’s work affiliated with university
- Yet another artwork outside the institution
- Additional artwork not done on campus
- Former cargo ship docked by Russian river outside city walls
- Discarded vehicle floating on river outside the building
- Old form of transport on river outside university
- Old art-form, painting without boundaries
- Unnecessary painting outside institution’s boundary
Buddy explains!

The straight part
We know that "outside the institution" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case outside the institution = extramural.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 EXTRAMURAL mean?
EXTRAMURAL adjective- Taking place outside the walls of an institution, especially a school or university.
- Describing teaching of students who are not resident at such an institution.