Get through exam period — a journey (7)
I believe the answer is:
'a journey' is the definition.
(I know that passage is a type of journey)
'get through exam period' is the wordplay.
'get through exam' becomes 'pass' (I've seen this before).
'period' becomes 'age' (age is a kind of period).
(Other definitions for passage that I've seen before include "Piece of writing" , "Corridor or narrow laneway" , "course" , "Sea or air journey" , "Book extract; transit" .)