Vulgar, vacuous character, fool (5)
I believe the answer is:
crass
'vulgar' is the definition.
(I've seen this in another clue)
'vacuous character fool' is the wordplay.
'vacuous' means to remove the middle letters.
'fool' becomes 'ass' (both can mean a stupid person).
'character' with its centre removed is 'cr'.
'cr'+'ass'='CRASS'
(Other definitions for crass that I've seen before include "Showing gross lack of sensitivity" , "Totally lacking in sensibility" , "'Gross, vulgar (5)'" , "Grossly insensitive" , "Indelicate" .)