Treatment for addiction (5)
I believe the answer is:
rehab
'treatment for addiction' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for rehab that I've seen before include "Process of restoring, eg, an addict to health" , "Restorative care" , "getting dry?" , "Health-restoring process" , "Course of treatment for addicts" .)