… one after another for speaking out can be put in prison (6)
I believe the answer is:
intern
'be put in prison' is the definition.
(I've seen this before)
'one after another for speaking out' is the wordplay.
'one after another' becomes 'in turn' (in turn means one by one).
'for speaking out' indicates a 'sounds like' (homophone) clue.
'inturn' is a homophone of 'INTERN'.
'can' is the link.
(Other definitions for intern that I've seen before include "22 [IMPRISON]" , "Confine the hospital resident" , "Incarcerate without trial - a junior hospital doctor?" , "Confine - physician in US hospital" , "(American) hospital doctor" .)