Worry upsets west (4)
I believe the answer is:
stew
'worry' is the definition.
(I've seen this in another clue)
'upsets west' is the wordplay.
'upsets' indicates anagramming the letters.
'west' anagrammed gives 'STEW'.
(Other definitions for stew that I've seen before include "anxious state" , "Slow cooked meat dish" , "overheated condition" , "Simmer" , "Cook by simmering in closed vessel" .)