Talk familiarly to a bird (4)
I believe the answer is:
chat
This clue is a double definition.
'talk familiarly' is the first definition.
(I've seen this before)
'bird' is the second definition.
(chat is a kind of bird)
'to a' acts as a link.
(Other definitions for chat that I've seen before include "Talk casually" , "Exchange text or voice messages through a computer" , "A bird; converse" , "Casual conversation" , "Friendly talk" .)