Area behind house in which cart backed? (4)
I believe the answer is:
yard
'area behind house' is the definition.
(garden or space behind a house)
'cart backed?' is the wordplay.
'cart' becomes 'dray' (a cart without sides for delivering heavy loads).
'backed?' shows that the letters should be reversed in order.
'dray' in reverse letter order is 'YARD'.
'in which' acts as a link.
(Other definitions for yard that I've seen before include "Space outside" , "Get the measure" , "3 feet" , "Thirty six inches" , "compound" .)