Lose sleep, maybe (4)
I believe the answer is:
fret
'lose sleep maybe' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for fret that I've seen before include "Worry - decoration - part of guitar" , "Bar on fingerboard of guitar" , "Guitar ridge; be anxious" , "Worry; or the marking on a guitar" , "Wear; guitar ridge" .)