So Sue's upset, being in a pickle! (5)
I believe the answer is:
souse
'a pickle' is the definition.
(I've seen this in another clue)
'so sue's upset' is the wordplay.
'upset' indicates an anagram.
'sue' anagrammed gives 'use'.
'so'+'use'='SOUSE'
'being in' is the link.
(Other definitions for souse that I've seen before include "Pickled meat" , "thoroughly wet" , "dip" , "Pickle - drunkard" , "Wash" .)