Predators initially unnerve rabbit (7)
I believe the answer is:
prattle
'rabbit' is the definition.
(both can mean to talk excessively)
'predators initially unnerve' is the wordplay.
'initially' suggests taking the first letters.
'unnerve' becomes 'rattle' (I've seen this in another clue).
The first letter of 'predators' is 'p'.
'p'+'rattle'='PRATTLE'
(Other definitions for prattle that I've seen before include "Talk childishly" , "Talk emptily" , "Childish talk" , "Chatter in childish way" , "Blether" .)