State main points again where MP bans duke (5)
I believe the answer is:
recap
'state main points again' is the definition.
I can't tell whether this definition defines the answer.
'mp bans duke' is the wordplay.
'mp' becomes 'redcap' (Military Police officers are called redcaps).
'bans' is a deletion indicator.
'duke' becomes 'd' (abbreviation).
'redcap' with 'd' removed is 'RECAP'.
'where' acts as a link.
Can you help me to learn more?
(Other definitions for recap that I've seen before include "Summarising statement" , "Go back over the main points" , "Review" , "Go over again in the mind" , "Go over again; summarise" .)