A smav is a smart chav; one who wears a suit to work, but generally has a head full of hair that is in disarray. A smav usually has trouble tying a proper knot in his tie; it's usually a big loose mess hanging around his neck, and the tie itself ends up ending halfway up his shirt.
Smavs usually refer to each other and their friends as 'bruv' and 'fella'.
Smavs tend to go to the toilet in groups for some reason, and they often neglect to wash their hands, as it doesn't matter; whatever's on their hands will go some way to styling their hair 'style'.
"Jesus, do your tie up properly; you look a right smav"
A Smart/Clever/intelectual Chav
"Hey, that chav over there just got an A On his test!"
"Oh, he must be a smav..."