Worry generated by guitar bar? (4)
I believe the answer is:
fret
I believe this is a double definition.
'worry' is the first definition.
(fretting is a kind of worrying)
'guitar bar?' is the second definition.
(fret is a part of a guitar)
'generated by' is the link.
(Other definitions for fret that I've seen before include "Show anxiety" , "Chafe, be anxious" , "Distress oneself" , "Display anxiety" , "Anguish" .)