Put in prison, we hear, one after the other (2,4)
I believe the answer is:
in turn
'one after the other' is the definition.
(I've seen this before)
'put in prison we hear' is the wordplay.
'put in prison' becomes 'intern' (I've seen this before).
'we hear' shows a homophone (sound like).
'intern' sounds like 'IN TURN'.
(Other definitions for in turn that I've seen before include "a succession of things happen" , "not out of place" , "orderly treatment" , "in an orderly fashion" , "One after another" .)