Small piece of land in place associated with Old Testament (4)
I believe the answer is:
plot
'small piece of land' is the definition.
'place associated with old testament' is the wordplay.
'place' becomes 'pl' (abbreviation used in postal addresses).
'associated with' means one lot of letters go next to another.
'old testament' becomes 'ot'.
'pl'+'ot'='PLOT'
'in' is the link.
(Other definitions for plot that I've seen before include "Area of ground; storyline" , "Conspire - small piece of land" , "garden area" , "bed" , "Machination" .)