Fence; complaining bitterly (7)
I believe the answer is:
railing
This clue is a double definition.
'fence' is the first definition.
(I've seen this before)
'complaining bitterly' is the second definition.
(I've seen this in another clue)
(Other definitions for railing that I've seen before include "Haranguing -- horizontal bar on supports" , "Fencing - complaining - attacking" , "complaints procedure?" , "barrier appears" , "Complaining - fence" .)