Didn’t allow to go off in the van (7)
I believe the answer is:
forbade
'didn't allow to go off in the van' is the definition.
I can't tell whether this definition defines the answer.
'didn't allow to go off in the' is the wordplay.
'didn't allow' becomes 'fo' (I can't justify this - if you can you should believe this answer much more).
'to go' becomes 're' (I've seen this in other clues).
'off' becomes 'bad' (I've seen this in other clues).
'in the' means one lot of letters goes inside another.
're' enclosing 'bad' is 'rbade'.
'fo'+'rbade'='FORBADE'
Can you help me to learn more?
(Other definitions for forbade that I've seen before include "banned" , "Disallowed" , "Vetoed" , "Prohibited" .)