Keeping secret a chastisement (6)
I believe the answer is:
hiding
'keeping secret' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for hiding that I've seen before include "big defeat" , "Concealment - severe defeat" , "Beating - retreat" , "corporal punishment" , "Keeping secret" .)