### Clue: Grass with criminal past put inside, becomes this? (8)
### Answer: REFORMED 
 ### Explanation: Definition: this
 REED(grass/a plant with a long stem) **containing**(with … put inside), FORM(a criminal past/a criminal record).
Defn: What a grass/one who informs on fellow criminals and with form might become after being put inside jail. A well-constructed, apt surface.