Complaining to the fence? (7)
I believe the answer is:
railing
I believe this clue is a double definition.
'complaining' is the first definition.
(railing is a kind of complaining)
'the fence?' is the second definition.
(I've seen this before)
'to' acts as a link.
(Other definitions for railing that I've seen before include "Barred metal fence" , "Fencing - rating" , "Barrier of a horizontal bar and supports" , "border of park?" , "Mocking" .)