Diana broadcast about total ban (8)
I believe the answer is:
disallow
'ban' is the definition.
(thesaurus)
'diana broadcast about total' is the wordplay.
'diana' becomes 'di' (Di is short for Diana).
'broadcast' becomes 'sow' (sowing is a kind of broadcasting**).
'about' means one lot of letters goes inside another.
'total' becomes 'all' (I've seen this before).
'sow' going around 'all' is 'sallow'.
'di'+'sallow'='DISALLOW'
(Other definitions for disallow that I've seen before include "Refuse to accept as valid, as judge might a claim" , "Rule out" , "Reject" , "Prevent" , "Prohibit, veto" .)