Odd moment with English souvenir (7)
I believe the answer is:
memento
'souvenir' is the definition.
(I know that memento is a class)
'odd moment with english' is the wordplay.
'odd' indicates anagramming the letters.
'with' is an insertion indicator.
'english' becomes 'e' (abbreviation).
'moment' is an anagram of 'memnto'.
'memnto' going around 'e' is 'MEMENTO'.
(Other definitions for memento that I've seen before include "Reminder of a person or event" , "Souvenir or token" , "Souvenir, reminder of past events" , "Souvenir, reminder of past event" , "This reminds" .)