Noise on backing tracks causing concern (5)
I believe the answer is:
worry
'concern' is the definition.
(I know that concern can be written as worry)
'noise on backing tracks' is the wordplay.
'noise' becomes 'row'.
'on backing' says the letters should be written backwards.
'tracks' becomes 'RY' (abbreviation for railway).
'row' reversed gives 'wor'.
'wor'+'ry'='WORRY'
'causing' is the link.
(Other definitions for worry that I've seen before include "Concern, anxiety, uneasiness" , "Fret, be disturbed in mind" , "'Anxiety, uneasiness (5)'" , "(Feel) anxiety" , "Harry" .)