Speaker is a bird (7)
I believe the answer is:
tweeter
I believe this is a double definition.
'speaker' is the first definition.
(tweeter is a kind of speaker)
'bird' is the second definition.
'is a' is the link.
(Other definitions for tweeter that I've seen before include "hi-fi unit?" , "piece of hi-fi" , "one delivering a short message?" , "One may follow another" , "Chirpy type" .)