Just tell me! (3,4,2)
I believe the answer is:
out with it
'just tell me' is the definition.
('out with it' encourages someone to say something)
This is all the clue.
(Other definitions for out with it that I've seen before include "Say what's on your mind, don't suppress it" , "Squeal" , "Speak up" , "Stop hesitating!" , "Demand for comment" .)