Pertaining to pitch (5)
I believe the answer is:
tonal
'pertaining to pitch' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tonal that I've seen before include "To do with vocal or musical sound" , "of pitch" , "Relating to conventional keys and harmonies" , "style of music" , "Written in conventional keys and harmony" .)