Sound familiar (4,1,4)
I believe the answer is:
ring a bell
'sound familiar' is the definition.
(something which seems familiar rings a bell)
This is the entire clue.
(Other definitions for ring a bell that I've seen before include "Call for servant" , "Make a chiming sound" , "may awaken memories" , "faintly resonate" , "Formally declare (appointment)" .)