Change includes a new act of atonement (7)
I believe the answer is:
penance
'act of atonement' is the definition.
(I've seen this before)
'change includes a new' is the wordplay.
'change' becomes 'pence' (I have seen 'Small change ' mean 'pence' so perhaps 'change' could also mean 'pence'**).
'includes' indicates putting letters inside.
'a new' becomes 'an' (I've seen this in other clues).
'pence' placed around 'an' is 'PENANCE'.
(Other definitions for penance that I've seen before include "Reparation" , "sackcloth and ashes?" , "Remorse" , "Act imposed for sin" , "Punishment for wrongdoing, by religion perhaps" .)