Point to a tree from the window (4)
I believe the answer is:
'window' is the definition.
(I've seen this before)
'point to a tree' is the wordplay.
'point' becomes 's' (South).
'to a tree' becomes 'ash' (ash is a kind of tree).
'from the' is the link.
(Other definitions for sash that I've seen before include "Strip of cloth - type of window" , "Band of cloth" , "Part of a window - decoration" , "Window frame - shoulder band" , "Type of sliding window" .)