Make prisoners terse over time (9)
I believe the answer is:
construct
'make' is the definition.
(constructing is a kind of making)
'prisoners terse over time' is the wordplay.
'prisoners' becomes 'cons'.
'terse' becomes 'curt' ('curt' can be a synonym of 'terse').
'over' says the letters should be written backwards.
'time' becomes 't'.
'curt' in reverse letter order is 'truc'.
'cons'+'truc'+'t'='CONSTRUCT'
(Other definitions for construct that I've seen before include "Get building" , "Engineer" , "Build or put parts together" , "Build, make" , "Build, fabricate" .)