A little time after, had become vicious (6)
I believe the answer is:
bitten
'become vicious' is the definition.
I can't tell whether this definition defines the answer.
'a little time after' is the wordplay.
'a little' becomes 'bit' (I've seen this in other clues).
'time' becomes 'ten' (I've seen this before**).
'after' is a charade indicator (letters next to each other).
'bit'+'ten'='BITTEN'
'had' acts as a link.
Can you help me to learn more?
(Other definitions for bitten that I've seen before include "Wounded (by a snake)" , "Stung" , "Once this, twice shy they say" , "Wounded (by a gnat, spider, etc)" , "Torn by teeth" .)