Symbol on a stave to show the pitch (4)
I believe the answer is:
clef
'symbol on a stave to show the pitch' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for clef that I've seen before include "Treble or bass sign?" , "Musical key or stave" , "Musical character" , "Musical notation on a staff" , "Staff note" .)