Talkative person (10)
I believe the answer is:
chatterbox
'talkative person' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for chatterbox that I've seen before include "one who talks a lot" , "Babbler" , "who goes on and on?" , "There's much talk from me" , "Gasbag" .)