Withdraw quietly and do penance in church monument (8)
I believe the answer is:
cenotaph
'monument' is the definition.
(cenotaph is a kind of monument)
'withdraw quietly and do penance in church' is the wordplay.
I cannot really see how this works, but
'withdraw' could be 'tap' (tapping is a kind of withdrawing) and 'tap' is found in the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is located in the answer.
'church' could be 'ce' (abbreviation for Church of England) and 'ce' is present in the answer.
The remaining letters 'oh' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for cenotaph that I've seen before include "Monument to people whose remains are interred elsewhere" , "Monument to those killed in war" , "Whitehall memorial" , "Monument honouring persons buried elsewhere" , "War memorial" .)