6-0 - fast and furious (7)
I believe the answer is:
violent
'furious' is the definition.
('violent' can be similar in meaning to 'furious')
'6-0 fast' is the wordplay.
'6' becomes 'vi' ('VI' can be a synonym of '6').
'0' becomes 'o' (I've seen this in other clues).
'fast' becomes 'lent' (I've seen this before).
'vi'+'o'+'lent'='VIOLENT'
'and' acts as a link.
(Other definitions for violent that I've seen before include "Furious" , "Brutal - intense" , "Using much force" , "Hot-headed" , "Extreme(ly aggressive)" .)