Make a move in prison (4)
I believe the answer is:
stir
I believe this clue is a double definition.
'make a move' is the first definition.
(I've seen this in another clue)
'prison' is the second definition.
(informal term for prison)
'in' acts as a link.
(Other definitions for stir that I've seen before include "created by an agitator?" , "Arouse; mix" , "Rotate spoon" , "College" , "Wake; disturbance" .)