Penny amends homework (11)
I believe the answer is:
preparation
'homework' is the definition.
('preparation' can be a synonym of 'homework')
'penny amends' is the wordplay.
'penny' becomes 'p'.
'amends' becomes 'reparation' ('reparation' can be a synonym of 'amends').
'p'+'reparation'='PREPARATION'
(Other definitions for preparation that I've seen before include "Specially made up medicine" , "getting ready" , "Iron parapet (anag.)" , "Homework" , "Preliminary measure" .)