Marines in studious assembly (7)
I believe the answer is:
seminar
'studious assembly' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'marines' is the wordplay.
'marines' can be anagrammed to 'SEMINAR'.
But, I'm not clear how the anagram is indicated.
'in' is the link.
Can you help me to learn more?
(Other definitions for seminar that I've seen before include "University course" , "Meeting for study" , "Student discussion group - remains (anag)" , "University discussion" , "workshop" .)