Conditional release of a prisoner (6)
I believe the answer is:
parole
'conditional release of a prisoner' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for parole that I've seen before include "Provisional release (for prisoner)" , "Early conditional release for prisoner in jail" , "Temporary release on promise of good behaviour" , "Give Al rope when he's released early" , "Release (a prisoner) on the promise of good conduct" .)