Lesson the marines disrupted (7)
I believe the answer is:
seminar
'lesson' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'marines disrupted' is the wordplay.
'disrupted' is an anagram indicator.
'marines' is an anagram of 'SEMINAR'.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for seminar that I've seen before include "workshop" , "Working meeting in College" , "Marines (anag.)" , "Short intensive study course for marines" , "Tutorial group meeting" .)