During prohibition, show disapproval of primate (6)
I believe the answer is:
baboon
'primate' is the definition.
(baboon is a kind of primate)
'during prohibition show disapproval' is the wordplay.
'during' is an insertion indicator.
'prohibition' becomes 'ban' (ban is a kind of prohibition).
'show disapproval' becomes 'boo' (I've seen this before).
'ban' enclosing 'boo' is 'BABOON'.
'of' acts as a link.
(Other definitions for baboon that I've seen before include "Large primate" , "Type of large monkey" , "Stupid person" , "animal" , "A large one of 17 across" .)