Reformed persons finally make comeback (8)
I believe the answer is:
response
'comeback' is the definition.
(I've seen this before)
'reformed persons finally make' is the wordplay.
'reformed' indicates an anagram.
'finally' says to take the final letters.
The final letter of 'make' is 'e'.
'persons' is an anagram of 'respons'.
'respons'+'e'='RESPONSE'
(Other definitions for response that I've seen before include "Rejoinder, retort" , "comeback" , "See porn (anag) -- answer" , "Sees porn (anag) - answer" , "Reaction, reply" .)