Emphatically (10)
(Other definitions for vehemently that I've seen before include "Intensely, forcefully" , "with force" , "Passionately, forcefully" , "with strong feeling" .)
'emphatically' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for in spades that I've seen before include "to a high degree" , "by the yard" , "how a contract may be agreed" , "Emphatically" , "to a large degree" .)