Wife takes everything to be a barrier (4)
I believe the answer is:
wall
'a barrier' is the definition.
(a wall acts as a barrier)
'wife takes everything' is the wordplay.
'wife' becomes 'w' (abbreviation).
'takes' is a charade indicator (letters next to each other).
'everything' becomes 'all' (all things).
'w'+'all'='WALL'
'to be' is the link.
(Other definitions for wall that I've seen before include "Stone fence" , "Solid barrier" , "Brick or stone barrier" , "Separator of Pyramus and Thisbe" , "mechanical part" .)