Deny, prohibit (6)
I believe the answer is:
forbid
I believe this is a double definition.
'deny' is the first definition.
(thesaurus)
'prohibit' is the second definition.
(I know that prohibit can be written as forbid)
(Other definitions for forbid that I've seen before include "Refuse permission, order not to" , "Ban" , "bar" , "Interdict" , "Deny, prohibit" .)