Where two walls meet (6)
I believe the answer is:
corner
'where two walls meet' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for corner that I've seen before include "Angle formed by two meeting walls" , "Where two lines meet to form an angle" , "Point where two walls meet" , "Where rook is immobilised, initially" , "pickle" .)