Be uneasy (4)
I believe the answer is:
fret
'be uneasy' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for fret that I've seen before include "Chafe, be anxious" , "Worry - pine" , "Be anxious -- part of a fingerboard" , "Worry; sort of saw" , "Split up" .)