Missing volume, gap occasionally vital — this is one example (5,4)
I believe the answer is:
inter alia
'this is one example' is the definition.
(Latin phrase meaning 'among other things')
I cannot understand how the rest of the clue works.
(Other definitions for inter alia that I've seen before include "Among other things, in Latin" , "among others" , "amongst others" , "Midst other things" , "amongst other things" .)