Vituperous about the vermin? (5)

I believe the answer is:
ratty
'vituperous about the vermin?' is the definition.
I can't judge whether this definition defines the answer.
'vituperous about the vermin?' is the wordplay.
'vituperous' becomes 'ty' (I can't explain this - if you can you should believe this answer much more).
'about' is a charade indicator (letters next to each other).
'the vermin?' becomes 'rat' (rats are vermin).
'ty' after 'rat' is 'RATTY'.
Can you help me to learn more?
(Other definitions for ratty that I've seen before include "Short-tempered" , "Irritable (informal)" , "Fictional mole's chum" , "Irritable, peevish" , "Bad-tempered, irritable as a rodent" .)
