Boorish character, vacuous idiot (5)
I believe the answer is:
crass
'boorish' is the definition.
(I've seen this before)
'character vacuous idiot' is the wordplay.
'vacuous' suggests removing the centre.
'idiot' becomes 'ass' (both can mean a stupid person).
'character' with its centre taken out is 'cr'.
'cr'+'ass'='CRASS'
(Other definitions for crass that I've seen before include "Insensitively stupid" , "Grossly stupid, tactless" , "Indelicate" , "Tactless, boorish" , "Asinine" .)