Wolfish? That's a nervous reaction! (8)
I believe the answer is:
ravenous
'wolfish?' is the definition.
(synonyms)
'a nervous reaction' is the wordplay.
'a nervous' can be anagrammed to 'RAVENOUS'.
But, I am unsure how this is indicated.
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for ravenous that I've seen before include "Voracious" , "needing to be fed" , "Really hungry, ready to devour" , "Intensely hungry" , "Extremely hungry" .)